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YELLOW FEVER 

A COMPILATION OF VARIOUS PUBLICATION 



RESULTS OF THE WORK OF MAJ. 
WALTER REED. MEDICAL CORPS. 
UNITED STATES ARMY. AND THE 
YELLOW FEVER COMMISSION 






PRESENTED BY MR. OWEN 



January 27. 1911.— Referred to the Committee on Printing. 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1911 




MAJ. WALTER REED, MEDICAL CORPS, U. S. ARMY. 



61 st Congeess ) SENATE I Document 

3d Session \ \ No. 822 



YELLOW FEVER 



A COMPILATION OF VARIOUS PUBLICATIONS 



7$y 



RESULTS OF THE WORK OF MAJ. 
WALTER REED, MEDICAL CORPS, 
UNITED STATES ARMY, AND THE 
YELLOW FEVER COMMISSION 



PRESENTED BY MR. OWEN 



January 27, 1911. — Referred to the Committee on Printing. 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1911 



o v 



« V 



o^ 



In the Senate of the United States. 
Feb. 17, 1911. 

Resolved, That there be printed, with accompanying illustrations, 
for the use of the Senate, one thousand copies of the compilation 
relative to the work of Major Walter Keed and the Yellow Fever 
Commission. 

Attest: Charles G. Bennett, 

Secretary. 
2 






PREFACE. 



The results of the work of Maj. Walter Reed, Medical Corps, 
United States Army, and the Yellow Fever Commission, of which he 
was president and the masterful mind, have been so beneficial and 
far-reaching that its importance is considered secondary to no other 
scientific achievement. 

The various publications in regard to Maj. Reed and his work and 
the reports of the commission, as well as other reports on subjects 
intimately connected with this work, while all extant and on file in 
the larger libraries of this country, are not available for the profes- 
sion in general. Being bound in one volume they will be much more 
available for general use, and will be less liable to be misplaced. 

Many of the younger men in the profession and in the Medical 
Corps of the Army are not so thoroughly conversant with the various 
steps of this work as is thought desirable. This work should be a 
source of inspiration for every medical officer. 

In compiling these various publications repetitions have been 
avoided as much as possible. However, the reports of Maj. Reed 
and his associates are considered of so much scientific as well as his- 
torical interest that they are published in full in chronological order. 
In this way the various steps in the experiments are more clearly 
shown. 

3 



TABLE OF CONTENTS. 



Page. 
Part I. — Walter Reed, the man, his work, and the appreciation shown of the 
results accomplished by him and his associates on the Yellow Fever Commi- 
sion: 

Chapter 1 . A memoir 7 

Chapter 2. Sketch of the life of Maj. Walter Reed 14 

Chapter 3. Messase from the President of the United States. December 5. 
1906. embodying letter from Brig. Gen. R. M. O'Reilly, Surgeon General 

United States Army 17 

Chapter 4. Senate Document Xo. 520, Sixty-first Congress, second session, 
embodying letter from Brig. Gen. George H. Torney, Surgeon General 

L nited" States Army 24 

Chapter 5. In memoriam; District of Columbia Medical Society 32 

Chapter 6. Value of Dr. Reed's work and expressions of appreciation 4^ 

Part II. — The publications of Walter Reed and his associates on the commis- 
sion in regard to yellow fever: 

Chapter 1. Bacillus icteroides and Bacillus choknr suis — A preliminary note. 

April 1 , 1S99 53 

Chapter 2. The Etiology of Yellow Fever — A preliminarv note, October. 

1900 ." 56 

Chapter 3. The Etioloev of Yellow Fever — An additional note, Februarv. 

1901 70 

Chapter 4. The Propagation of Yellow Fever — Observations based on recent 

researches, April, 1901 90 

Chapter 5. Experimental Yellow Fever, May, 1901 110 

Chapter 6. The Prevention of Yellow Fever", September, 1901 131 

Chapter 7. The Etioloev of Yellow Fever — A supplemental note. Januarv, 

1902 .' '. . 149 

Chapter 8. Recent Researches Concerning: the Etiology, Propagation, and 
Prevention of Yellow Fever, by The United States Arrnv Commission 

(three charts', April, 1902 161 

Part III. — The publications of James Carroll, assistant surgeon. I nited States 
Army, in regard to yellow fever (published after the death of Maj. Reed : 

Chapter 1. The Transmission of Yellow Fever, May, 1903 175 

Chapter 2. Remarks on the Epidemic of Yellow Fever in Baltimore. Feb- 
ruary, 1905 - 

Chapter 3. Yellow Fever — A popular lecture, April, 1905 195 

Chapter 4. Lessons to be Learned from the Present Outbreak of Yellow 

Fever in Louisiana. September, 1905 216 

Part IV. — Reports from sanitary officers in Habana, Cuba, demonstrating the 
practical value of the scientific findings of Maj. Reed and his associates on the 
Yellow Fever Commission: 

Chapter 1. Report of Col. Yalery Havard. February, 1901 221 

Chapter 2. Report of Charles Finlay, chairman of trie Habana Yellow Fever 

Commission, January. 1902 " 227 

Chapter 3. Report of Maj. W. C. Gorgas, Medical Corps, L'nited States 

Army, July, 1902 234 

Part Y. — A few general directions with regard to destroying mosquitoes, par- 
ticularly the yellow-fever mosquito, by Col. William C. Gorgas. Medical 
Corps, United States Army '. 239 

5 



PART L— WALTER REED— THE MAN, HIS WORK, AND THE APPRECIA- 
TION SHOWN OF THE RESULTS ACCOMPLISHED BY HIM AND HIS 
ASSOCIATES ON THE YELLOW FEVER COMMISSION, 



Chapter 1. 

WALTER REED.— A MEMOIR. 1 
By Walter D. McCaw, Major, Medical Corps, United States Army. 

It is given to but few scientific men to lay bare a secret of nature 
materially affecting the prosperity of nations, and the lives, fortunes, 
and happiness of thousands. Fewer still succeed in so quickly con- 
vincing brother scientists and men in authority of the truth of their 
discoveries that their own eyes behold the glorious result of their 
labor. 

Of the 51 years of Walter Reed's industrious, blameless life, 12 
only were spent in the study of the special branch of science in which 
he became famous, but his name now stands with those of Jenner, 
Lister, and Morton as among the benefactors of humanity. 

Walter Reed was born in Gloucester County, Va., September 13, 
1851, the son of the Rev. Lemuel Sutton Reed and Pharaba White, 
his wife. 

The circumstances of his family were modest, and some of the 
years of his boyhood were spent in a much troubled section of the 
south during the great Civil War. He acquired, however, a good 
preliminary education, and at an age when most boys are still in 
the schoolroom he began the study of medicine at the University of 
Virginia, graduating as M. D. in 1869, when only 17 years old. 

A second medical degree was received later from Bellevue Medical 
College, New York, and then came terms of service in the Brooklyn 
City Hospital, and the City Hospital, Blackwell's Island. 

Before the age of 21 Reed was a district physician in Xew York 
City, and at 22 one of the five inspectors of the board of health of 
Brooklyn. 

He entered the Army of the United States as assistant surgeon 
with the rank of first lieutenant, in 1875, and for the next 18 years, 
with the usual varying fortunes of a young medical officer of the 
Army, he served in Arizona, Nebraska, Dakota, and in the Southern 
and Eastern States. 

According to the exigencies of the service he was moved frequently 
from station to station, everywhere recognized by men of his own 
age as a charming and sympathetic companion, and by older officers 

1 Washington, D. C. Published by the Walter Reed Memorial Association, 1904. 



8 YELLOW FEVEE. 

as an earnest and intelligent physician, whose industry, fidelity to 
duty, and singularly clear judgment, gave brilliant promise for the 
future. In the poor cabins and dugouts of the pioneers in the 
sparsely settled districts where he served his flag, Reed was ever a 
messenger of healing and comfort. At that time Army posts on the 
frontier were usually remote and with small garrisons. The young 
medical officer, generally the only one at the station, was called upon 
by the settlers for miles around. Without help, and with only such 
instruments and medicines as could be hastily stuffed in his saddlebag, 
he was summoned to attend a fractured thigh, a child choking with 
diphtheria, or, most trying of all, a complicated childbirth. 

Such experience schools well in self-reliance, and in the formation 
of quick and accurate observation. 
J^ For a man like Reed, already an earnest student, no better prepara- 
tion could perhaps have been had. His earlier Army service must 
have singularly tended to develop in him the very qualities most 
necessary to his final success. To the end of his life it was noticeable 
that even when he had long given up the practice of medicine for the 
work of the laboratory, he was nevertheless unexcelled at the bedside 
for rapid, unerring diagnosis and sound judgment in treatment. So 
also were the series of experiments which robbed yellow fever of its 
terrors especially remarkable for simplicity, accuracy, and complete- 
ness, or they never would have so quickly convinced the world of 
their truth. Too much reverence for accepted teachings, and too 
little experience in grappling with difficulties unassisted, and they 
might never have been conceived or carried out. 

In 1890 he was assigned to duty in Baltimore and remained there 
over a year. Here he had the great advantage of working in the 
laboratories of Johns Hopkins University and the happiness of win- 
ning the close friendship of his distinguished teacher, Prof. William 
H. Welch. 

In 1893, Reed was promoted surgeon with the rank of major, 
and in the same year was detailed in Washington as curator of the 
Army Medical Museum and professor of bacteriology at the newly 
organized Army Medical School. Here he worked industriously at 
his specialty and wrote many valuable monographs, all charac- 
terized by accuracy and originality. His excellent judgment made 
him especially valuable in investigating the causes of epidemic dis- 
eases at military posts, and in making sanitary inspections. He 
was, therefore, frequently selected for such work, which with his 
duties as teacher and member of examining boards, occupied much 
of the time that he would otherwise have spent in his laboratory. 
Here again it seems that duties which must often have been irksome 
were specially fitting him for his culminating work. 

During the Spanish-American war the camps of the volunteer 
troops in the United States were devastated by typhoid fever, and 
Maj. Reed was selected as the head of a board to studv^ the causation 
and spread of the disease. This immense task occupied more than 
a year's time. With the utmost patience and accuracy the details 
of hundreds of individual cases were grouped and studied. The 
report of the commission, now in course of publication by the Gov- 
ernment, is a monumental work which must always serve as a basis 
for future study of the epidemiology of typhoid fever. 



YELLOW FEVER. 9 

The most original and valuable work of the board is the proof t 
that the infection of typhoid fever is spread in camps by the com- I 
mon fly, and by contact with patients and infected articles, clothing, | 
tentage, and utensils, as well as by contaminated drinking water. 

In June, 1900, Maj. Reed was sent to Cuba as president of a board w 
to study the infectious diseases of the country, but more especially a 
yellow fever. Associated with him were Acting Asst. Surgs. James 
Carroll, Jesse W. Lazear, and A. Agramonte. 

At this time the American authorities in Cuba had for a year and 
a half endeavored to diminish the disease and mortality of the Cuban 
towns, by general sanitary work, but while the health of the popu- 
lation showed distinct improvement and the mortality had greatly v 
diminished, yellow fever apparently had been entirely unaffected by 
these measures. In fact, owing to the large number of nonimmune 
foreigners, the disease was more frequent than usual in Habana and 
in Quemados near the camp of American troops, and many valuable 
lives of American officers and soldiers had been lost. 

Reed was convinced from the first that general sanitary measures 
alone would not check the disease but that its transmission was prob- 
ably due to an insect. 

The fact that malarial fever, caused by an animal parasite in the 
blood, is transmitted from man to man through the agency of certain 
mosquitoes had .been recently accepted by the scientific world; also N 
several years before Dr. Carlos Finlay, of Habana, had advanced the 
theory that a mosquito conveyed the unknown cause of yellow fever, 
but did not succeed in demonstrating the truth of his theory. 

Dr. H. R. Carter, of the Marine-Hospital Service, had written a 
paper showing that although the period of incubation of yellow fever 
was only 5 days, yet a house to which a patient was carried did 
not become infected for from 15 to 20 days. 

To Reed's mind this indicated that the unknown infective agent v 
has to undergo a period of incubation of from 10 to 15 days, and 
probably in the body of a biting insect. 

Up to this time the most generally accepted theory as to the causa- 
tion of yellow fever was that of Sanarelli, who claimed that the 
Bacillus icteroides discovered by him was the specific agent of the 
disease. Maj. Reed in association with Dr. Carroll had, however, 
already demonstrated that this bacillus was one widely disseminated 
in the United States, and bore no special relation to } T ellow fever. 

In June, July, and August, 1900, the commission gave their entire 
attention to the bacteriological study of the blood of yellow-fever 
patients and the post-mortem examinations of the organs of those 
dying with the disease. In 24 cases where the blood was repeatedly 
examined, as well as in 11 carefully studied autopsies, Bacillus 
icteroides was not discovered, nor was there any indication of the 
presence in the blood of a specific cause of the disease. 

Application was made to Gen. Leonard Wood, the military governor 
of Cuba, for permission to conduct experiments on nonimmune 
persons, and a liberal sum of money requested for the purpose of 
rewarding volunteers who would submit themselves to experiment. 

It was indeed fortunate that the military governor of Cuba was a 
man who by his breadth of mind and special scientific training could 
readily appreciate the arguments of Maj. Reed as to the value of the 
proposed work. 



10 YELLOW FEVER. 

Money and full authority to proceed were promptly granted, and to 
the everlasting glory of the American soldier, volunteers from the 
Army offered themselves for experiment in plenty and with the utmost 
fearlessness. 

Before the arrangements were entirely completed, Dr. Carroll, a 
member of the commission, allowed himself to be bitten by a mosquito 
that 12 days previously had filled itself with the blood of a yellow- 
fever patient. He suffered from a very severe attack, and his was 
the first experimental case, Dr. Lazear also experimented on himself 
at the same time, but was not infected. Some days later, while in 
the yellow-fever ward, he was bitten by a mosquito and noted the 
fact carefully. He acquired the disease in its most terrible form and 
died a martyr to science and a true hero. 

No other f atality occurred among the brave men who, in the course 
of the experiments, willingly exposed themselves to the infection of 
the dreaded disease. 

A camp was especially constructed for the experiments about 4 
miles from Habana, christened Camp Lazear in honor of the dead 
comrade. The inmates of the camp were put into most rigid quar- 
antine and ample time was allowed to eliminate any possibility of 
the disease being brought in from Habana. 

The personnel consisted of three nurses and nine nonimmunes, all 
in the military service, and included two physicians. 

From time to time Spanish immigrants, newly arrived, were 
brought in directly from the immigrant station; a person not known 
to be immune was not allowed to leave camp, or if he did was for- 
bidden to return. 

The most complete record was kept of the health of every man to 
be experimented upon, thus eliminating the possibility of any other 
disease than yellow fever complicating the case. 

The mosquitoes used were specially bred from the eggs and kept 
in a building screened by wire netting. When an insect was wanted 
for an experiment it was taken into a yellow fever hospital and 
allowed to fill itself with the blood of a patient; afterwards at varying 
intervals from the time of this meal of blood it was purposely applied 
to nonimmunes in camp. 

In December, 5 cases of the disease were developed as the result of 
such applications; in January, 3, and in February, 2, making in all 
10, exclusive of the cases of Drs. Carroll and Lazear. Immediately 
upon the appearance of the first recognized symptoms of the disease, 
in any one of these experimental cases, the patient was taken from 
Camp Lazear to a yellow-fever hospital, 1 mile distant. Every person 
in camp was rigidly protected from accidental mosquito bites, and 
not in a single instance did yellow fever develop in the camp, except 
at the will of the experimenters. 

The experiments were conducted at a season when there was the 
least chance of naturally acquiring the disease, and the mosquitoes 
used were kept active by maintaining them at a summer temperature. 

A completely mosquito-proof building was divided into two com- 
partments by a wire-screen partition; infected insects were liberated 
on one side only. A brave nonimmune entered and remained long 
enough to allow himself to be bitten several times. He was attacked 
by yellow fever, while two susceptible men in the other compartment 
did not acquire the disease, although sleeping there 13 nights. This 



YELLOW FEVER. 11 

demonstrates in the simplest and most certain manner that the infec- 
tiousness of the building was due only to the presence of the insects. 

Every attempt was made to infect individuals by means of bedding, 
clothes, and other articles that had been used and soiled by patients 
suffering with virulent yellow fever. 

Volunteers slept in the room with and handled the most filthy 
articles for 20 nights, but not a symptom of yellow fever was noted 
among them, nor was their health in the slightest degree affected. 
Nevertheless they were not immune to the disease, for some of them 
were afterwards purposely infected by mosquito bites. This experi- 
ment indicates at once the uselessness of destroying valuable property 
for fear of infection. Had the people of the United States known 
this one fact 100 hundred years ago, an enormous amount of money 
would have been saved to householders. 

Besides the experimental cases caused by mosquito bite, four non- 
immunes were infected by injecting blood drawn directly from the 
veins of yellow-fever patients in the first two days of the disease, 
thus demonstrating the presence of an infectious agent in the blood at 
this early period of the attack. 

Even the blood serum of a patient, passed through a bacteria-proof 
filter, was found to be capable of causing yellow fever in another 
person. 

The details of the experiments are most interesting, but it must 
here suffice to briefly sum up the principal conclusions of this admirable 
board of investigators of which Reed was the master mind: 

1 . The specific agent in the causation of }~ellow fever exists in the 
blood of a patient for the first three days of his attack, after which 
time he ceases to be a menace to the health of others. 

2. A mosquito of a single species, Stegomyia fasciata, ingesting the 
blood of a patient during this infective period is powerless to convey 
the disease to another person by its bite until about 12 days have 
elapsed, but can do so thereafter for an indefinite period, probably 
during the remainder of its life. 

3. The disease can not in nature be spread in any other way than 
by the bite of the previously infected Stegomyia. Articles used and 
soiled by patients do not carry infection. 

These conclusions pointed so clearly to the practical method of 
exterminating the disease that they were at once accepted by the 
sanitary authorities in Cuba, and put to the test in Habana, where 
for nearly a century and a half, by actual record, the disease had 
never failed to appear annually. 

In February, 1901, the chief sanitary officer in Habana, Maj. W. C. 
Gorgas, Medical Department, United States Army, instituted meas- 
ures to eradicate the disease, based entirely on the conclusions of the 
commission. Cases of yellow fever were required to be reported as 
promptly as possible, the patient was at first rigidly isolated, and 
immediately upon the report a force of men from the sanitary depart- 
ment visited the house. All the rooms of the building and of the 
neighboring houses were sealed and fumigated to destroy the mos- 
quitoes present. Window and door screens were put up, and after 
the death or recovery of the patient, his room was fumigated and 
every mosquito destroyed. A war of extermination was also waged 
against mosquitoes in general, and an energetic effort was made to 
diminish the number bred by draining standing water, screening tanks 



12 YELLOW FEVEK. 

and vessels, using petroleum on water that could not be drained, and 
in the most systematic manner destroying the breeding places of the 
insects. 

When the warm season returned a few cases occured, but by Sep- 
tember, 1901, the last case of yellow fever originated in Habana, since 
which time the city has been entirely exempt from the terrible dis- 
ease, that had there kept stronghold for 150 years. Cases are now 
admitted into Habana from Mexican ports, but are treated under 
screens with perfect impunity, in the ordinary city hospitals. The 
crusade against the insects also caused a very large decrease in mala- 
rial fevers. 

The destruction of the most fatal epidemic disease of the Western 
Hemisphere, in its favorite home city is but the beginning of the 
benefit to mankind that may be expected to follow the work of Reed 
and his associates. There can be no manner of doubt should Mexico, 
Brazil, and the Central American Republics, where the disease still 
exists, follow strictly the example set by Habana, that yellow fever 
will become extinct and the United States forever freed from the 
scourge that has in the past slain thousands of our citizens and 
caused the loss of untold treasure. 

More recent investigations into the cause and spread of yellow 
fever have only succeeded in verifying the work of Reed and his 
commission in every particular and in adding very little to our knowl- 
edge of the disease. 

Later researches by Guiteras in Habana, by the Public Health and 
Marine-Hospital Service in Vera Cruz, and lastly by a delegation from 
the Pasteur Institute of Paris in Rio de Janeiro, all confirm in the 
most convincing manner both the accuracy and comprehensiveness 
of the conclusions of the American commission. It has been well 
said that Reed's experiments "will always remain as models in the 
annals of scientific research, both for the exactness with which they 
were adapted to the points to be proved, and the precautions taken 
that no experiment should be vitiated by failure to exclude all possible 
sources of error." 

Appreciation of Reed's work was instant in the scientific world. 
Honorary degrees from Harvard University and the University of 
Michigan were conferred upon him, learned societies and distinguished 
men delighted to honor him, and after his death Congress voted a 
special pension to his widow. 

To the United States the value of his services cannot be estimated. 
Ninety times has yellow fever invaded the country, carrying death 
and destruction, leaving poverty and grief. 

New Orleans, Memphis, Charleston, Galveston, Portsmouth, Balti- 
more, Philadelphia, New York, and many smaller towns have been 
swept by the disease. 

The epidemic of 1853 cost New Orleans 8,000 lives, that of 1793 
wiped out 10 per cent of Philadelphia's population. 

The financial loss to the United States m the one epidemic of 1878 
was estimated as amounting to $15,335,000, but suffering^ panic, 
fear, and the tears of widows and orphans can never be estimated. 
Now, however, if yellow fever should again cross our southern 
border, there need be no disturbance of commerce or loss of prop- 
erty in the slightest degree comparable with that which epidemics 
in the past have caused. 



YELLOW FEVER. 13 

The death of Maj. Reed took place November 23, 1902, in Wash- J 
ington, from appendicitis. It is gratifying to think that, although 
his country and the scientific world were deprived of one from 
whose future services more benefit to humanity might reasonably be 
expected, nevertheless he was privileged before his life's close to 
know that his discovery had been tested, and that a great city was 
freed from her ancient foe, to know that his conscientious work had 
contributed immeasurably toward the future prospects of an infant 
Republic, and even more to the welfare of his own beloved country, 
whose flag he had served so faithfully. 

In the national capital and in the great cities of the United 
States, there are stately monuments to the country's great ones. 
Statues of warriors, statesmen, and patriots stand as silent wit- 
nesses of a people's gratitude. Is there not room for the effigy of 
Walter Reed, who so clearly pointed out to his fellow man the way 
to conquer America's worst plague ? 



Chapter 2. 

SKETCH OF THE LIFE OF MAJ. WALTER REED, SURGEON 
UNITED STATES ARMY. avw^vn, 

By Jefferson R. Kean, Major, Medical Corps, United States Army. 

Walter Keed, M D., LL. D., M. A., major and surgeon United 
States Army, was born September 13 185*1, in Gloucester 'CoXty 
utjrf*^ - the S ? n , of the Kev. Lemuel Sutton Reed, a leading 
S? dlS l dmM K 0f that Sta J e - His ancestOTS came from North 
«?£ « 'l ^ n , an ?° n ? the earliest settlers of that colony. He 
gave early evidence of the intellectual brilliancy and earnestness of 
purpose which distinguished him in later years, and graduated i ? n 
medicine at the University of Virginia in 1869. He afterwards took 
the degree of M. D. in Bellevue Medical College, New York City He 

hosT,1t fl ] a L rT 6 ^ 1 ?! 60 ?/ 11 7 16 ^klyn Cit y Hos P ital Md ^e city 
hospital on Blackwells Island, and before the age of 21 was appointed 

of tt r fil P - lly81Cl r m ?S W York City. He was also appointed one 
of the five inspectors of the board of health of the city of Brookl y n 

H W 22 - *? 187 l he ente / ed the Medical Cor P s °f the Army" 
S^r i J yea f th . ereafter Performed the customary duties of a 
fnr T n a 1° ^°T/ T a - nous 1 P 0Sts m ^erent parts of the United States 
and in the field. His military service included 15 changes of station, 
with 4 years in Arizona, 5 m the Department of the Pfatte, 2 in the 
Department of Dakota, 3 in the South, and 3 years in the East. He 
was promoted full surgeon with the rank of major December 4 1893 

MSiLlfj 6 T ° f + hi f i 6 \ th Was ^ st on the list of ma 3°rs 'in the 
Medical Department of the Army. In the fall of 1890 he was assigned 
to duty as attending surgeon in Baltimore, Md., which position he 
held for a year. He promptly embraced this opportunity to make 
special studies m bacteriology and pathology, and soon won the atten- 
tion and esteem of Prof. William H. Welch. This was the beginning 
or a close friendship with that distinguished scientist which lasted 
until the untimely death of Maj. Keed, on November 23 1902 

In 1893 Maj Reed was placed on duty in Washington as curator 
or the Army Medical Museum and appointed the professor of bacte- 
riology of the newly organized Army Medical School. 

In the 10 years subsequent to this date, in the intervals of his 
routine duties and others which came to him as a medical officer, such 
as member of examining boards, teaching, investigation of numerous 
sanitary questions, and making sanitary inspections, he was able, b V 
immense industry, to obtain a position in the scientific world such as 
comes to tew of those who are able to devote a lifetime exclusively to 
such pursuits; J 

Of the numerous monographs which show his scientific work during 
tnis time, all are creditable; nor do any show marks of carelessness or 
haste, in spite of the limited time which he had at his disposal 



YELLOW FEVER. 15 

In 1898, when typhoid fever prevailed so extensively in the camps 
of the Volunteer Armies of the United States, Maj. Reed was put at 
the head of a commission — Dr. Victor C. Vaughan, of the University 
of Michigan, and Dr. E. O. Shakespeare, of Philadelphia, being the 
other members — to study the causation and methods of spread of that 
disease. This investigation, which covered a period of more than a 
year, was remarkable for the patience and skill with which a vast 
number of details were assembled and studied, and it marks a great 
advance in our knowledge of this widespread disease. Among the 
points of great value brought out were the importance of the common 
ny as a carrier of infection in camps, and the frequency with which 
the contagion of typhoid fever is in camp life spread from man to 
man by immediate contact with each other or with bedding, tents, 
and implements which have become infected. Strangely enough, this 
report has never been published in full, but only an abstract of it 
containing some 240 pages, and, on account of the failure to publish 
and disseminate the full report, its conclusions are but little known 
abroad or among the members of the medical profession in this 
country. Many of the facts contained in it were rediscovered by 
the English during the Boer War, and it is probable that its prompt 
publication and dissemination would have saved many thousand lives 
during that war. 

The first work by Maj. Reed bearing on the causation of yellow V 
fever was in 1899-1900, when he overthrew the claim of the dis- 
tinguished bacteriologist, Sanarelli, to have discovered the bacillus of 
yellow fever, by his demonstration that the Bacillus icteroides (Sana- 
relli) was an organism widely disseminated in this country and having 
no causative relation to that disease. He began the special work with 
which his name will always be inseparably associated as one of the ben- 
efactors of mankind in June, 1900, when he went to Cuba as presi- 
dent of a commission to study the infectious diseases of Cuba, with 
special reference to yellow fever. The other members of tins commis- 
sion were Acting Asst. Surgs. James Carroll, Jesse W. Lazear, and 
A. Agramonte. The time was most opportune for such investigation, 
as the disease was at that time prevalent both in Habana and in the 
little town of Quemados, near the camp of the American troops, and 
it was plainly evident that the energetic measures of the American 
military government to clean up the towns, disinfect, and enforce 
other sanitary measures were without effect in preventing the spread 
of this particular disease. Maj. Reed became convinced that proper 
sanitation was not all that was needed, and that some other agent than 
unclean conditions was responsible for the spread of the disease. 

The transmission of malaria by a certain species of mosquito had 
been recently demonstrated by the English military surgeon, Ronald 
Ross. The theory had also been advanced both by a Mobile physician 
and by Dr. Finlay, of Habana, that a mosquito was the agent for the 
transmission of yellow fever; but these theories, being unsupported 
by scientific demonstration, received no more attention than the vast 
number of others which had been at one time or another advanced 
with regard to this mysterious and deadly disease. 

Dr. Reed's attention was attracted by a paper on the spread of yellow 
fever in Ormond, Miss., by Dr. H. R. Carter, of the Marine-Hospital 
Service, in which it was shown that although the period of incuba- 
tion of the disease was 5 days, 15 or 20 elapsed before a house 



1" YELLOW FEVEB. 



became infected after a patient sick with yellow fever was carried into 
it He inferred that the difference between the time of inluKon and 
the time required to infect a building was due to the fact thai tht 

ZZ'wt- ag6nt P f Sed tl ? r ° Ugh a sta « e of development in the bo! of 
Wn^ ltm A™ sect as an intermediate host, and he at once determined 
to conduct his experiments along that line. It was evident to his 3 
that the solution of tins question, which meant so much for the human 
race, could never be satisfactorily determined without experimenTon 
human beings, and he went to Gen. Wood, the military P go™mo r of 
Cuba, to ask permission to conduct such experiments, and for a sum 
of money to liberally reward volunteers who should si bmit theT 
selves for experiment. Gen. Wood promptly granted boSi with a" 
ready appreciation of the importance of tlie mftter and the force of 

Se as o/tirditvirf 11 ^ entitie wm to - ■»* --- of 

who had offered themselves as the first volunteers for these exneri' 
ments, had demonstrated that mosquitoes would convey velowK' 

?tr' a ckT, / r' h ° WM , the fi rs V XperimentaI case - suffered a verjsevere 
attack but recovered. Dr. Lazear was not infected at this time due 

Lt.t\^ ^ c f ondlti ° nS n8CeSSar y t0 the transmission of the 
disease by the mosquito were not yet understood, but he was bitten 
while working m the yellow-fever ward somewhat later, and died a 
martyr of science, working in behalf of humanity. This was the onlv 
fatality which occurred in these experiments, the fourth member or 
w^nf?? 1881011 ' ° r - . A S ram onte, di d not participate in the mosquito 
work of the commission until a later date, nor did he share their dan- 
gers, as he was a Cuban and immune 

Immediately upon Dr. Reed's return arrangements were made with 
the assistance of the military governor, as stated above, for a serieTof 
experiments which, by precision of detail and rigidness of control 
would admit of no uncertainty of interpretation and would be a per- 
fect demonstration, carrying conviction to everv scientific and 
wEiiWeTrS Th6Se ex P erim ents will, as stated by Profi 

reseat Lrl thl JS T mam •"? m ? de s in the annals of s «entific 
research, both for the exactness with which they were adapted to the 

s P h°ou d t ^A°7i a ? d , the P reca V ti o*s taken that no experiment 
should be vitiated by failure to exclude all possible sources of error. 

iTSt?w! f m a W C t mp es P e o ia % constructed for the pur- 
fZ't^rt ^' e ; S from H u abana . and appropriately named "Camp 
Lazear., The history of the work is best given in Dr. Keed's own 

Engtd 1 an PUMlShed in ° le Joumal of Hygiene, Cambridge^ 



Chapter 3. 

EXPERIMENTS CONDUCTED FOR THE PURPOSE OF COPING WITH 

YELLOW FEVER. 

[Senate Document No. 10, Fifty-ninth Congress, second session.] 

To the Senate and House of Representatives: 

The inclosed papers are transmitted to the Congress in the earnest 
hope that it will take suitable action in the matter. Maj. Reed's 
part in the experiments which resulted in teaching us how to cope 
with yellow fever was such as to render mankind his debtor, and this 
nation should in some proper fashion bear witness to this fact. 

Theodore Roosevelt. 

The White House, December, 5. 1906. 



[Inclosure 1.] 
[Memorandum for the President, through The Military Secretary of the Army.[) 

War Department, 
Office of the Surgeon General, 

YYashington, August 30, 1906. 

The persons taking an important part in the investigations in 
Cuba, which resulted in the demonstration of the fact that yellow 
fever is transmitted by a species of mosquito, were three members of 
the board appointed to investigate epidemic diseases in Cuba — 
Walter Reed, James Carroll, and Jesse W. Lazear — and the indi- 
viduals who submitted themselves for experimentation by receiving 
the bites of infected mosquitoes, by receiving injections of blood from 
yellow-fever patients, and by sleeping in bedding which had been 
used by yellow-fever patients. 

When the Yellow Fever Commission, composed of Walter Reed, 
James Carroll, Jesse W. Lazear, and A. Agramonte, assembled in 
Habana they had no thought of investigating the connection of the 
mosquito with the spread of yellow fever. This idea came to Dr. 
Reed after the board had demonstrated that the claim of Sanarelli, 
concurred in by Wasdin and Geddins, that the Bacillus icteroides 
was the cause of yellow fever was without foundation. Dr. Reed 
then determined to investigate the theory of Dr. Carlos Finlay, 
that the mosquito was instrumental in conveying yellow fever, which 
theory Finlay had failed to demonstrate, and which was not then 
accepted by scientific men. This determination was reached for the 
reasons which are well stated in Dr. Kelly's biography, and was 
original with Reed, not being suggested to him by anyone. The 
final determination to investigate the mosquito theory was arrived at 
during an informal meeting of the board (Dr. Agramonte being 
absent) at Columbia Barracks on the evening before Dr. Reed's 
79965°— S. Doc. 822, 61-3 2 17 



18 YELLOW FEVER. 

departure for the United States, early in August, 1901. It was 
agreed by these members of the board that in making the experi- 
ments on human beings, by which alone the demonstration could be 
made, that they should submit themselves as subjects for experimen- 
tation. To Dr. Lazear, who was familiar with mosquito work, was 
assigned the duty of breeding and infecting the mosquitoes, while 
Dr. Carroll was to continue the bacteriological work on which the 
board had been engaged. 

On August 2, 1900, before the mosquitoes were ready for the 
experiment, Dr. Reed was called back to Washington to prepare 
for publication the abstract of the report of the board appointed in 
1898 to investigate the spread of typhoid fever in the volunteer 
camps in the United States, of which board he was president. This 
vast work, of which the full report was published by special authority 
of Congress about a year after Dr. Reed's death, by the only sur- 
viving member of the board, Prof. Victor C. Vaughan, of the Uni- 
versity of Michigan, was one of the most valuable contributions to 
science which has been made by the Surgeon General's Office. The 
work of preparation of the abstract report had been brought to a 
standstill by the sudden death of the third member of the board, 
Dr. Edward O. Shakespeare, of Philadelphia, and Dr. Reed's presence 
at this time was essential for its completion. 

During Dr. Reed's absence the inoculations by means of the 
mosquito were begun. On August 11, Dr. Lazear made the first 
experiment, but nine distinct inoculations on persons, including him- 
self and Acting Asst. Surg. A. S. Pinto, were unsuccessful. We know 
now that these failures were due to two facts — first, that patients 
after the third day of the disease can not convey the infection to the 
mosquito, and second, that after having bitten a yellow-fever case the 
mosquito can not transmit the disease until after an interval of at 
least 12 days. On August 27 one mosquito was applied to Dr. 
Carroll, one which happened to fulfill both of these conditions. The 
result was a very severe attack of yellow fever, in which for a time 
his life hung in the balance. This was thus the first experimental 
case. The fever developed on the 31st of August, on which day Dr. 
Lazear applied the same mosquito which bit Dr. Carroll with three 
others to another person. This man came down with a mild but 
well-marked case. 

On September 13 Dr. Lazear, while on a visit to Las Animas 
Hospital (for the purpose of collecting blood from yellow-fever 
patients for study) was bitten by a mosquito of undetermined species, 
which he deliberately allowed to remain on the back of his hand until 
it had satisfied its hunger. Five days thereafter he came down, 
without other exposure, with yellow fever, which progressed steadily 
to a fatal termination. These three cases established in Reed's mind 
the proof of the mosquito theory and made it, in the opinion of his 
friends, an unnecessary and foolish risk for him, at his age, to submit 
himself to inoculation. These cases, with his deductions therefrom, 
were reported by the board in a paper called "The etiology of yellow 
fever — A preliminary note," read before the American Public Health 
Association at Buffalo, N. Y., October 22-26, 1900. He then 
immediately returned to Cuba to undertake a second and more 
elaborate series of experiments which were made possible by the 
promise made to him by Gen. Wood on October 12, when told by 



YELLOW FEVER. 19 

Reed of the experiments already made, to assist him with whatever 
money was necessary. This, the second series of experiments, began 
Xovember 20 at an experimental camp near Quemados, caUed Camp 
Lazear, and embraced 14 cases, of which the last was taken sick 
February 10, 1901. Of these. 10 were mosquito infections and 4 
were infected by injection of the blood of yellow-fever patients. All 
of these cases recovered. 

A third series of 6 cases was produced by Dr. James Carroll 
the next fall to settle certain undetermined facts as regards the 
etiology of the disease. The first of these cases came down with 
the fever September 19, 1901, and the last on October 23, 1901. Of 
these cases 2 were caused by mosquitoes and 4 by blood injec- 
tions. Xone of them resulted fatally. The highly dangerous char- 
acter of these experiments and the good fortune of the board in its 
second and third series of cases is shown by the fact that Dr. Guiteras, 
of Habana. in a series of 7 cases inoculated in Habana lost 3, bring- 
ing his experiments abruptly to an end. 

Xo enumeration of unsuccessful cases — namely, those which failed 
to cause the disease — has been made, although it is obvious that the 
persons undergoing such experiments exhibited as much courage as 
those in which the disease was transmitted. This is especially true 
of the cases occurring after the severe case of Dr. Carroll and the 
fatal case of Dr. Lazear. Certain ones of these unsuccessful cases 
deserve special mention, being those made with infected bedding 
at Camp Lazear. In a specially constructed house at that camp, 
which was intentionally ill ventilated and kept continually at a 
summer temperature, was placed a large quantity of bedding taken 
from the beds of patients sick with yellow fever in Habana and 
soiled with their discharges. In this house Acting Asst. Surg. R. P. 
Cook and two privates of the Hospital Corps slept continuously 
from Xovember 30 to December 19. Each morning they packed the 
various soiled articles of bedding in boxes and unpacked them at 
night, when they were used to sleep on. 

From December 21, 1900. to January 10, 1901, the building was 
again occupied by two nonimmune Americans under the same cir- 
cumstances, except that an additional stock of very much fouled 
bedding and clothing had been added to the collection, and these 
men slept every night in the very garments worn by yellow-fever 
patients throughout their entire attacks, besides making use of their 
much soiled piUow slips, sheets, and blankets. A third couple of 
Hospital Corps men succeeded these for an equal length of time. 
Xone of these seven individuals contracted yellow fever, but the 
courage and fortitude shown by them certainly equal that of those 
who submitted to the bites of the mosquitoes, it being borne in mind 
that belief hi the transmission of yellow fever by infected bedding 
and clothing was at that time practically universal, whereas the 
mosquito theory had still very few converts. 

After this brief history of this great discovery a statement of the 
part borne by each of the more important participators in it is 
necessary to a determination of the reward which would be appro- 
priate to each. 

Maj. Walter Reed, surgeon, United States Army, president of the 
commission to investigate and study the epidemic diseases in Cuba, 
died in Washington from appendicitis, Xovember 23, 1902, at the 



20 YELLOW PEVEE. 

age of 51. At the time of his death the Secretary of War had said in 
his report, which was then in press but not yet given out : 

The brilliant character of this scientific achievement, its inestimable value to 
mankind, the saving of thousands of lives, and the deliverance of the Atlantic seacoast 
from constant apprehension, demand special recognition from the Government of 
the United States. 

Dr. Reed is the ranking major in the Medical Department, and within a few months 
will, by operation of law, become lieutenant colonel. I ask that the President be 
authorized to appoint him Assistant Surgeon General with the rank of colonel. 

Gen. Leonard Wood said of him in an address delivered at a 
memorial meeting of scientific men in Washington, D. C, shortly 
after his death: 

I know of no other man on this side of the world who has done so much for humanity 
as Dr. Reed. His discovery results in the saving of more lives annually than were 
lost in the Cuban war, and saves the commercial interests of the world a greater finan- 
cial loss each year than the cost of the Cuban war. He came to Cuba at a time when 
one-third of the officers of my staff died of yellow fever, and we were discouraged at 
the failure of our efforts to control the disease. 

In the months when the disease was ordinarily worst the disease was checked 
and driven from Habana. That was the first time in nearly 200 years that the city 
had been rid of it. The value of his discovery can not be appreciated by persons 
who are not familiar with the conditions of tropical countries. Hereafter it will never 
be possible for yellow fever to gain such headway that quarantine will exist from the 
mouth of the Potomac to the mouth of the Rio Grande. Future generations will 
appreciate fully the value of Dr. Reed's services. His was the originating, directing, 
and controlling mind in this work, and the others were assistants only. 

In a letter from Prof. Welch to the Secretary of War he said : 

Dr. Reed's researches in yellow fever are by far the most important contributions to 
science which have ever come from any Army surgeon. In my judgment they are 
the most valuable contributions to medicine and public hygiene which have ever 
been made in this country with the exception of the discovery of anaesthesia. They 
have led and will lead to the saving of thousands of lives. I am in a position to know 
that the credit for the original ideas embodied in this work belongs wholly to Maj. 
Reed. 

Prof. Welch was Dr. Reed's teacher in bacteriology and was his 
intimate and confidential friend, with whom he consulted about the 
details of the work in Cuba. 

A bill prepared in this office for a pension for his widow, equal in 
amount to his monthly pay, was passed, but the amount was so cut 
down that while it keeps the wolf from the door it does not pro- 
vide an adequate and comfortable income. It is not probable, how- 
ever, that Congress would increase this pension, and an effort has 
been made to supplement it by the raising of a fund of $25,000 by the 
Walter Reed Memorial Association, incorporated for this purpose 
in the District of Columbia. The interest on this fund will be given 
Mrs. Reed during her lifetime, and the principal, after her death, will 
be devoted to some form of memorial. This fund lacks at present 
about $6,000 of completion. The existence of this association, should 
its hopes be attained, does not, however, absolve the nation from the 
obligation of a fitting recognition for this great work, and it is the 
opinion of the undersigned, which, it is believed, is shared by, the 
vast majority of physicians in the United States, that Congress 
should erect a statue to Walter Reed in Washington. The assistance 
of the President in inducing Congress to do so is requested. 

The second member of the commission was Dr. James Carroll, at 
that time acting assistant surgeon, United States Army. 

Dr. Carroll is now 52 years old. He entered the military service 
June 9, 1874, and served as private, corporal, sergeant, and hospital 



YELLOW FEVER. 21 

steward from that date to May 21, 1898, when he was appointed acting 
assistant surgeon. He was appointed first lieutenant and assistant 
surgeon in the Medical Corps October 27, 1902, which rank he still 
holds. 

Dr. Carroll was Dr. Reed's truest assistant and coadjutor from the 
inception of the work which resulted in the discovery of the method 
of propagation of yellow fever. As stated above, the third series of 
experiments were performed by Dr. Carroll alone, Dr. Reed having 
been refused permission to return to Cuba to complete his work. 

Dr. Carroll was the first experimental case of yellow fever, and he 
suffered a very severe attack, to which he attributes a heart trouble 
from which he now suffers. At the time of undergoing this experi- 
ment he was 46 years old, an age at which the risk from this disease 
is very great, as its mortality rapidly increases with age of patient. 
He had at that time a wife and five children who had no other means 
of support except his pay as an acting assistant surgeon. 

It is recommended that Congress be asked to pass a special act pro- 
moting Dr. Carroll, on account of his services in connection with this 
discovery and the courage shown by him insubjecting himself to experi- 
ment, to the rank of lieutenant colonel, the number of medical officers 
in that grade being increased by one for that purpose ; also his name 
and effigy should appear on the monument to Walter Reed. 

Dr. Jesse W. Lazear was the third member of the commission. 

Dr. Lazear was a native of Baltimore and a graduate of Johns Hop- 
kins University, afterwards getting his professional degree at Columbia 
University and Bellevue. At the time he incurred his death in the 
course of these experiments, as above mentioned, he was 34 years 
old. He left a wife and two young children, the younger a little son 
born a few months before his death, whom he never saw. Mrs. Lazear 
received from Congress a pension of $17 a month with $2 additional 
for each of two minor children until they reach the age of 16. Also 
a battery in Baltimore Harbor was, by direction of the Secretary of 
War, named in his honor. It is believed that this recognition on the 
part of the nation for his services is utterly inadequate. His widow's 
pension should be increased to $100 a month, and steps should be 
taken to perpetuate his name in connection with the Walter Reed 
monument above suggested. 

Dr. A. Agramonte was the fourth member of the Yellow Fever 
Commission. He was a Cuban by birth, an immune to yellow fever, 
and having been assigned other work, took no part in the first series 
of experiments with regard to the conveyance of the disease by the 
mosquito, of which, in fact, he was not at the time cognizant. Being 
an immune, he ran no risk in connection with this work, and it is 
believed that his contributions to it have been sufficiently recognized 
in the association of his name with the other members of the com- 
mission who brought about this great discovery. 

Twenty-three of the men who submitted themselves for experiment 
by the board contracted yellow fever, beginning with Dr. James Car- 
roll, who was taken sick August 31, 1900, and ending with John R. 
Bullard, who was taken sick October 23, 1901. 

Conspicuous among them was John J. Moran, a civilian clerk 
employed at the headquarters of Gen. Fitzhugh Lee, at Quemados, 
who was one of the earliest volunteers for the second set of experi- 
ments, and whose action was dictated by the purest motives of 



22 YELLOW FEVER. 

altruism and self-devotion. Mr. Moran disclaimed, before submitting 
to the experiments, any desire for reward, and has never accepted any 
since, although he was offered the $200 which the liberality of the 
military governor enabled the commission to give to each experi- 
mental patient, the members of the board excepted. Such was his 
modesty that he has made no effort, so far as known to this office, to 
make known his connection with these experiments and reap the 
credit which is so justly due him. Mr. Moran was a native of Ohio. 
His present address is not known to this office. The first inoculations 
in the case of Mr. Moran were for some reason unsuccessful, on Novem- 
ber 26 and 29. He did not suffer an attack until after the third 
inoculation, on December 21. 

The same remarks apply to the first experimental case of the second 
set, Pvt. John K. Kissinger, hospital corps, who volunteered at the 
same time with Moran and equally disclaimed any desire for reward. 

Pvt. Kissinger did not leave Cuba immediately after the experi- 
ments, as did Mr. Moran, and therefore the military authorities were 
able to reward him in some measure along with other enlisted men 
who volunteered for these experiments. He was promoted acting 
hospital steward, presented with a gold watch by the chief surgeon 
of the department in the presence of all the medical officers and hos- 
pital corps men on duty at Columbia Barracks, and also received a 
present of $115 in cash. He took his discharge November 14, 1901, 
and has since (on December 17, 1903) made application for pension. 
This was refused for lack of evidence that his ill-health was incident 
to the service. 

Of the other experimental cases, seven were Spanish immigrants 
who submitted to experiments purely for the money which they were 
promised. With regard to those who were American soldiers, how- 
ever, 10 in number, in addition to those already mentioned, it can 
not be doubted that, although they received pecuniary rewards, a 
desire to assist in what they appreciated was a great and glorious 
work, together with a spirit of adventure, was the most powerful 
motive. The same is true of the last experimental case, Mr. John R. 
Bullard, a graduate of Harvard, where he was a distinguished athlete 
and captain of the university crew. The names of these men, with 
the dates of their attack, is appended with this report. 

It remains to mention Dr. Robert P. Cook, acting assistant surgeon, 
and the six privates of the hospital corps, who were for 20 nights 
shut up in the infected bedding house at Camp Lazear. These 
experiments, which were absolutely necessary to demonstrate that 
yellow fever could not be carried otherwise than by the mosquito, 
had for these men, so far as they knew, an equal element of danger 
with the other experiments and had in addition such repulsive 
and disagreeable features as to test to the full their hardihood and 
patience. Much of the bedding upon which they slept and which 
they were required daily to handle, was so soiled with the discharges 
of the sick as to be very repulsive to the nose and eye, and the last 
experimenters actually slept in the pajamas and sheets which had 
been worn by severe cases of yellow fever. The names of these 
men are appended to the list given below of experimental cases of 
yellow fever. 

It will be observed that three of these men — Folk, Jernegan, and 
Hanberry — afterwards submitted to the mosquito inoculation or 



YELLOW FEVER. 



23 



blood injection in order to demonstrate their nonimmunity at the 
time of the first experiment. 

It is believed that the names of all the Americans on this list 
should be placed on a tablet in connection with the monument to 
Walter Reed. 

From the foregoing it will be seen that the total disbursements 
of this great nation in the way of rewards for those who made possible 
this discovery and their families, amounts to $146 a month. As to 
its value to the American people attention is invited to the quota- 
tions from Gen. Wood and rrof . Welch given above, and others given 
in the inclosed circulars published by the Walter Reed Memorial 
Association. 

How discreditable appears this niggardly provision when com- 
pared with the action of the English Government which more than 
a century ago, when the purchasing power of money was far greater 
than at present, gave to Jenner, the discoverer of vaccination, grants 
amounting to £30,000 sterling. He also received from a subscrip- 
tion in India £7,383 sterling, while the Reed Memorial has so far 
succeeded in raising only a little over half that sum. 

It is believed that if the President would exert his great personal 
influence in furtherance of the aims of that association its task 
would be soon completed. 

R. M. O'Reilly, 
Surgeon General, United States Army. 



Names of persons who submitted to experimental inoculation of yellow fever, Cuba, 

1900-1901. 





Taken sick. 


1 


Jamas Carroll 


Infected by mosquitoes. 


Aug. 
Sept. 
Dec. 
Dec. 
I 
Dec. 
Dec. 
Jan. 
Jan. 
Feb. 
Feb. 
Feb. 
Sept 
Oct. 

Jan. 
Jan. 
Jan. 
Jan. 
Oct. 
Oct. 

Oct. 
] 


31,1900 


9! 


X. Y. (American soldier) . 
John "R. TCissingpr 




6,1900 


3 




8,1900 


4 


Nicanor Fernandez 


13,1900 


.5 


Antonio Benigno . 


)o. 


6 


Becente Presedo 




15,1900 


7 


John J. Moran 


25,1900 


8 


Jose Martinez 


3,1901 


9 


Levi E . Folk 


23,1901 


10 


Clyde L. West 


3,1901 


11 


James L. Hanbeny 


9,1901 


1? 


Charles G. Sonntag 


10,1901 


13 


Pablo Ruiz Castillo 


19, 1901 


14 


Jacinto Mendez Alvarez 


13.1901 


1 


Warren G. Jernegan 


Infected by injection of blood. 


8,1901 


2 


William Olson 


11,1901 


3 


Wallace Forbes 


24, 1901 


4 


John H. Andrus 


28,1901 


B 


• Manuel Gutierrez Moran 


20, 1901 


6 


John R. Bullard 


23, 1901 


1 


Infect 

P. Hamann, Twenty-third 
A. W. Covington, Twenty- 

Dr. R. P. Cooke, acting as: 
Levi E. Folk 


cd by injections of filtered blood serum. 
Battery Coast Artillery 


19, 1901 


2 


third Battery Coast Artillery 


)0. 


1 


Exposed to fomites. 




?, 






3 


Warren G. Jernegan 




4 


James L. Hanberrv 




5 


Edward Weatherwalks (bi 
James Hildebrand (offered 
Thomas M. England 


tten once, negative: refused after Hanberrv came down) 




fi 


himself, but was declined on account of age) 




7 













Chapter 4. 

YELLOW-FEVER COMMISSION. 

[Senate Document No. 520, Sixty-first Congress, second session.] 

War Department, 
Office of the Surgeon General, 

Washington, April 29, 1910. 

My Dear Senator: It gives me great pleasure to comply with 
the request contained in your letter of April 20, to furnish you with a 
report of the occurrences which led to the appointment of the yellow- 
fever commission, of which Maj . Walter Reed was president, and the 
names of the persons connected with the experiments of the com- 
mission, together with other data which is available concerning them. 

Surg. Gen. Sternberg was for many years one of the leading 
authorities in the world on the subject of yellow fever, and had made, 
under the direction of the President of the United States, very 
laborious investigations as to its cause in Habana, Brazil, and Mexico. 
These investigations were unsuccessful because, as we now know, the 
organism of yejlow fever is invisible to the microscope, but they 
served a valuable purpose in enabling Dr. Sternberg to disprove 
the claims of other investigators to have discovered the causative 
organism and to have prepared protective inoculations against the 
disease. His attention having been attracted by the claim of Sana- 
relli, of Buenos Aires, to have discovered the cause of yellow fever 
in the Bacillus ideroides, he ordered Maj. Reed, at that time pro- 
fessor of bacteriology in the Army Medical School, to study this 
organism in connection with an organism discovered by Sternberg 
in the bodies of yellow-fever patients in Habana, and named by him 
bacillus X. This investigation was continued by a board consisting 
of Maj. Walter Reed, surgeon, United States Army, and Acting 
Asst. Surgs. James Carroll, Aristides Agramonte, and Jesse W. 
Lazear, United States Army, which was appointed to meet at Camp 
Columbia, near Habana, Cuba, in May, 1900. The instructions to 
Maj. Reed, president of this board, included the following: 

You will naturally give special attention to questions relating to the etiology and 
prevention of yellow fever. As you are familiar with what has already been done by 
other bacteriologists in this field of investigation, I do not consider it necessary to give 
you any suggestions or detailed instructions . But it is evident that the' most important 
question which will occupy your attention is that which relates to the etiology of this 
disease. 

You will also take advantage of such opportunities as may offer for the study of other 
infectious diseases, and especially of the malarial fevers prevailing in the island of 
Cuba. An important question in connection with the diseases of tropical and semi- 
tropical countries relates to the etiology of febrile attacks of short duration, to which 
strangers are especially subject. Should you have time, there will be ample oppor- 
tunity for the study of leprosy in the lepers' hospital in the city of Habana. Attention 
should also be given to the infectious disease of the lower animals, in case any such 
prevail, the etiology of which has not been definitely determined. 

24 



YELLOW FEVEE. 25 

One member of the board, Dr. Aristides Agramonte, lived in 
Habana, and another, Dr. Jesse W. Lazear, was already stationed at 
Columbia Barracks, having joined there on February 13, 1900. The 
remaining members of the board arrived in Cuba June 25, 1900. 
They were able to prove conclusively that in 18 cases of unmistakable 
yellow fever investigated from beginning to end baciUus icteroides was 
not present and that this organism could not be the cause of the dis- 
ease. These conclusions were diametrically opposite to those of Drs. 
Wasdin and Geddings, of the Marine-Hospital Service, who likewise 
at that time were studying yellow fever in Habana, and who con- 
firmed the findings of Sanarelli. The board then proceeded to investi- 
gate the theory advanced by Finlay, that yellow fever was conveyed 
by mosquitoes. A full history of these experiments has been pub- 
lished in the reports of the board, and a brief account of it, together 
with a list of the persons who submitted to experimental inoculation, 
was given in a memorandum prepared for the President by this office 
on August 30, 1906, and transmitted as a special message to Congress 
on December 5, 1906. It was published as Senate Document No. 10, 
Fifty-ninth Congress, second session, a copy being inclosed. 

Before taking up individually the men concerned in these experi- 
ments, in order to state what is known about them at the present 
time, it may be mentioned that the Spaniards who were inoculated 
did so for the pecuniary inducement offered them. After receiving 
the reward offered them by the liberality of the military government 
of Cuba, $200 for each person successfully inoculated, they passed 
from the scene and nothing further is known concerning them. 
While their names should be preserved as a matter of historical 
interest, it is considered that they have been well rewarded for their 
share in the matter, especially as the idea of assisting in the advance- 
ment of science was not a controlling motive for their action. Also 
it should be stated that it can not be demonstrated that these experi- 
ments caused the death or subsequent ill health of any of the partici- 
pants, with the exception of Dr. Lazear and of three individuals who 
died in the course of the experiments which were conducted by Maj. 
Gorgas and Dr. John Guiteras at Las Animas Hospital, Habana, 
between February and December, 1901, which will be referred to later. 

In view of the facts which have come to the attention of this office 
since the preparation of the memorandum for the President, it is 
beheved that that memorandum does not do justice to the importance 
of the part which Dr. Agramonte took in these investigations. Dr. 
Agramonte has made the following statement with regard to the 
work of the board. 

In the investigations of the board with reference to BaciUus icteroides, Dr. Carroll 
had the bacteriological work, Dr. Agramonte the autopsy and gross pathology, Dr. 
Jesse W. Lazear the microscopical pathology. 

In June, 1900, Dr. Agramonte was sent to the city of Santa Clara to investigate the 
outbreak of yellow fever in that city, and in July he was sent to the city of Pinar del 
Rio to investigate the outbreak of yellow fever among the American troops, which 
the surgeons stationed there had failed to recognize as such. Dr. Agramonte promptly 
recognized the true character of the disease, and was joined there by Maj. Reed a 
couple of days later. It was there that for the first time the probability of mosquito 
agency in transmitting the disease was seriously discussed by members of the board, 
and it was decided to carry out some research in this direction. 

As Dr. Lazear had obtained considerable training in mosquito work while in Italy, 
and none of the other members of the board had any, it was agreed that he take up 
this part of the work in the beginning. Dr. Carroll continued to investigate the 
bacteria and Dr. Agramonte the pathological anatomy of yellow fever. 



26 YELLOW FEVER. 

Maj. Reed at this time returned to Washington for the purpose of completing the 
report upon "Typhoid Fever in the Army," in collaboration with Drs. Shakespeare 
and Vaughan. 

Lazear began to breed, dissect, classify, and infect mosquitoes, in which work Carroll 
and Agramonte took little or no part. Now and then Lazear would apply them to 
whoever allowed it. Most of the mosquitoes died early in captivity. Lazear, Carroll, 
and several other persons had been bitten several times by mosquitoes which pre- 
viously had fed on yellow fever blood, without result, so that the theory of mosquito 
transmission was gradually being discredited, until Carroll fell sick, on the 30th of 
August (1900), entirely innocent of the real nature of his illness. 

Suspecting the origin of his. infection and its real gravity, Drs. Lazear and Agra- 
monte decided to test the mosquito which presumably had caused Carroll's attack by 
applying it to the first nonimmune individual who might allow it. 

Therefore, on the afternoon of August 31, the same mosquito and three others, were 
applied to an American soldier who had not left Columbia Barracks (which was free 
from yellow fever) for 57 days prior to his inoculation ; nor did he go out of said reser- 
vation before he fell sick with yellow fever, five days afterwards, thus confirming in 
our minds the fact that he had been infected by the mosquito bites. 

Dr. Carroll being at this time still suffering from a severe attack of the disease, 
Drs. Lazear and Agramonte decided to communicate these results to Maj. Reed, who 
was yet in Washington. 

Before Maj. Reed's arrival in Habana, Dr. Lazear became infected with yellow 
fever, his death taking place on the 25th of September. 

During Carroll's convalescence, the board decided that the results of the investiga- 
tion were so far sufficiently convincing to justify their presentation, in the shape of a 
preliminary note, before the coming meeting of the American Public Health Association 
at Indianapolis, Ind. (October, 1900). 

Maj. Reed went north for this purpose, and while Carroll took a short vacation, to 
recuperate from his recent attack, Dr. Agramonte was charged with breeding and 
infecting mosquitoes, keeping them at the division laboratory, which was under his 
care in Habana, in preparation for the work which the board intended to carry out 
after the Indianapolis meeting. 

When Maj. Reed returned from the States, moral and material aid was obtained 
from Gen. Leonard Wood, commanding the division, and we determined to carry 
out an investigation exclusively based upon the mosquito theory sustained by Finlay; 
we knew nothing of Beauperthuy then, who in 1853 had defended practically the 
same theory. 

While the experimental station, afterward named Camp Lazear, in honor to the 
memory of our deceased colleague, was being established, the care of the mosquitoes 
and their infection by applying them to yellow-fever cases, was in the hands of Dr. 
Agramonte, at the division laboratory; when the permanent "mosquito building" was 
erected at Camp Lazear (Dec. 1, -1900), these mosquitoes were turned over to Dr. 
Carroll for his care. It devolved then upon Dr. Agramonte to select the mosquitoes 
from those kept by Dr. Carroll and apply them to nonimmunes, as well as to make all 
subsequent direct inoculations, and to obtain the nonimmunes (Spaniards) for the 
purpose, until the end of the work in Cuba. 

Let me add that the best friendship existed between all the members of the board, 
and from the beginning of their work it was agreed that the honor of the results was 
to be shared by all alike, as the labor was so evenly shared. Unfortunately this has 
not been the case, let us hope through no fault of the members themselves. Drs. 
Reed and Carroll had been connected in laboratory work for several years, and Dr. 
Agramonte had also worked at the Army Medical Museum Laboratory; Drs. Lazear 
and Agramonte were classmates, having graduated from the College of Physicians and 
Surgeons, New York, in June 1892. 

I certify to the absolute truth of the above statement. 

In testimony whereof I affix my signature in the city of Habana, August 31, 1908. 

Aristides Agramonte, M. D. 

1. Maj. Walter Heed, surgeon, United States Army ; died in Wash- 
ington, D, C, from appendicitis, November 23, 1902, aged 51. His 
widow, Emilie Lawrence Keed, is receiving a pension of $125 a month. 

2. Maj. James Carroll was promoted from first lieutenant to major 
by special act of Congress March 9, 1907. He died in Washington, 
D. C, of myocarditis, September 16, 1907. His widow, Jennie H. 
Carroll, since his death has received an annuity of $125 a month, 
appropriated from year to year in the Army appropriation bill. 



YELLOW FEVEK. • 27 

3. Dr. Jesse W. Lazear, contract surgeon, United States Army, died 
at Camp Columbia, Cuba, of yellow fever, September 25, 1900. His 
widow, Mabel M. Lazear, since his death has received an annuity of 
$125 a month, appropriated from year to year in the Army appropria- 
tion bill. 

4. Dr. Aristides Agramonte is the only living member of the board. 
He is professor of bacteriology and experimental pathology in the 
University of Habana and has never received, either directly or indi- 
rectly, any material reward for his share in the work of the board. 

5. The name of the American soldier, XY, who was the subject of 
the second experiment, was concealed at the time, because the experi- 
ment was made without military authorization. It has been recently 
ascertained to be William H. Dean, private, Troop B, Seventh Cav- 
alry. He has never received any reward. He was discharged August 
17, 1902, by reason of expiration of term of service, and there is no 
further record of him at the War Department. His residence at 
enlistment was given as Grand Rapids, Mich. His case has special 
importance as having been the first experimental case which was com- 
plete in the matter of control, for Dr. Carroll's, which came four 
days earlier, was defective, by reason of his going into the infected 
zone during the period of incubation. 

6. John R. Kissinger, private, Hospital Corps (see p. 6, President's 
message). Kissinger volunteered for service at the beginning of the 
Spanish War in Company D, One hundred and fifty-seventh Indiana 
Volunteers, and after his discharge enlisted in the Hospital Corps. 
After the first secret experiments of the board, which included the 
cases of Dr. Carroll and Pvt. Dean, became known and the experi- 
mental camp was established and named Camp Lazear, Kissinger 
and Moran were the first to volunteer as subjects for experiment. 
Moran was first bitten, but Kissinger was the first to be attacked, on 
December 8, 1900. He recovered and was afterwards promoted to 
be acting hospital steward, and discharged November 14, 1901, at 
Columbia Barracks, Cuba. It is understood that his health after- 
wards failed so that he became entirely dependent upon the labor of 
his wife for support. He was pensioned at the rate of $12 per month, 
by the act of March 2, 1907. This amount is considered quite 
inadequate either for his support or as a recognition of his services. 
A bill granting an increase to $125 per month was favorably reported 
and incorporated in Senate bill 6272 and passed the Senate February 
15, 1910, but was objected to by the Committee on Pensions of the 
House of Representatives. The report of the Senate committee (No. 
574) is inclosed. 

7. John J. Moran (see n. 6, President's message). Mr. Moran has 
never received any material reward for his most creditable services. 
After leaving Cuba he completed his education by a course of study 
at the University of Virginia, and is at present living at Panama, in 
the employ of the Isthmian Canal Commission. He is at present an 
applicant for appointment in the Consular Service for which, by reason 
of his excellent knowledge of Spanish and other qualifications, he is 
well fitted. 

8. Levi E. Folk, private, Hospital Corps, volunteered to be bitten 
by infected mosquitoes and was taken with yellow fever January 23, 
1901. He is still in the military service, and is a sergeant, Hospital 
Corps, stationed at the recruit depot, Columbus Barracks, Ohio. 



28 YELLOW EEVEB. 

He received a donation of $300 from the appropriation made by Gen. 
Leonard Wood for these experiments. 

9. Clyde L. West, private, Hospital Corps, volunteered to be bitten 
by infected mosquitoes at Camp Lazear, and was taken sick with 
yellow fever February 3, 1901. He was discharged from the service 
July 10, 1902, at Fort Myer, Va., and his subsequent address is 
unknown. He received a donation of $200 from the appropriation 
made by Gen. Leonard Yfood for these experiments. 

10. James L. Hanberry, private, Hospital Corps, volunteered to 
be bitten by infected mosquitoes, and in consequence, was taken sick 
with yellow fever at Camp Lazear February 9, 1901. He deserted 
the service April 4, 1902, at the general hospital, Washington Bar- 
racks, D. C. His subsequent address is unknown. He received a 
donation of $300 from the appropriation made by Gen. Wood for 
these experiments. 

11. Charles G. Sontag, private, Hospital Corps, volunteered to be 
bitten by infected mosquitoes, and was in consequence taken sick 
with yellow fever at Camp Lazear February 10, 1901. He was dis- 
charged from the service December 12, 1901, at Columbia Barracks, 
Cuba, and his subsequent address is unknown. He received a dona- 
tion of $200 from the appropriation made by Gen. Leonard Wood for 
these experiments. 

12. Warren Gadsden Jernegan, private, Hospital Corps, was 
infected with yellow fever by the injection of blood, and taken sick 
January 8, 1901. He was discharged November 16, 1901, at Colum- 
bia Barracks, Cuba. Address given, care of M. A. Fowler, McMeekin, 
Fla. He received a donation of $300 from appropriation made by 
Gen. Wood for these experiments. 

13. William Olsen, private, Hospital Corps, was infected with 
yellow fever by injection of blood, at Camp Lazear, and taken sick 
January 11, 1901. He was discharged November 15, 1901, at 
Columbia Barracks, Cuba. Address given, care of C. Olsen, Plum 
City, Wis. He received a donation of $200 from the appropriation 
made by Gen. Wood for these experiments. 

14. Wallace W. Forbes, private, Hospital Corps, volunteered to be 
infected with yellow fever by the injection of blood, at Camp Lazear, 
and became sick January 24, 1901. He was discharged March 1, 
1905, at Fort Hancock, N. J. Address given, care of J. W. Forbes, 
Minneapolis, Minn. This soldier received a donation of $200 from 
the appropriation made by Gen. Wood. 

15. John H. Andrus, private, Hospital Corps, volunteered and was 
infected with yellow fever by injection of blood, at Camp Lazear, and 
became sick January 28, 190L He was discharged April 24, 1902, 
at Camp Geo. H. Thomas, Chickamauga, Tenn. His subsequent 
address is not known. He received a donation of $200 from the 
appropriation made by Gen. Wood. 

16. John R. Bullard, native of Massachusetts, a graduate of 
Harvard University, where he was a distinguished _ athlete, and 
engaged in farming in Cuba, volunteered and was infected with 
yellow fever by the injection of blood. He became sick October 23, 
1901. 

17. Paul Hamann, private, Twenty-third Company, Coast Artillery, 
volunteered and was infected with yellow fever by injection of filtered 
blood serum and became sick October 19, 1901. He was discharged 



YELLOW FEVER. 29 

July 19, 1902, by reason of expiration of term of service. His address 
given at time of enlistment was care of August Hamann, Moline, 111. 
Present address not known. This soldier received a donation from 
the appropriation made by Gen. Wood for these experiments. 

18. Albert W. Covington, private, Twenty-third Company, Coast 
Artillery, volunteered and was infected with yellow fever by injection 
with filtered blood serum and became sick October 19, 1901. He is 
still in the service, and is serving as sergeant, Twenty-third Company, 
Coast Artillery Corps, at Fort McKinley, Portland, Me. He received 
a donation from the appropriation made by Gen. Wood for these 
experiments. 

19. Dr. Robert P. Cook (see President's message, p. 7). Dr. Cook 
entered the medical service June 9, 1900, as contract surgeon, from 
the State of Virginia. He left the service at his own request, Decem- 
ber 22, 1904. His present address is Winchester, Va. 

The demonstration made by Dr. Cook and the men with him that 
yellow fever could not be transmitted by infected clothing and other 
inanimate objects was of the utmost importance to commerce and 
has immensely simplified the preventive measures to be taken against 
this disease. He was shut up in a house with infected bedding for 
20 days, together with the following privates of the Hospital Corps, 
who received a donation of $100 each from the appropriation given 
by Gen. Wood for these experiments: 

20. Edward Weatherwalk. Discharged the service December 12, 
1901, at Columbia Barracks, Cuba. Subsequent address not known. 
He received a donation of $200. 

21. James Hildebrand. Still in service as private, first class, 
Hospital Corps; stationed at the recruit depot, Columbus Barracks, 
Ohio. He received a donation of $100. 

22. Thomas M. England. Still in service as sergeant, first class, 
Hospital Corps; stationed at Fort Ward, Wash. He received a 
donation of $100. 

In addition to these, Pvts. Folk, Jernegan, and Hanberry under- 
went the exposure to infected bedding prior to being bitten by the 
infected mosquitoes. 

Additional experiments by Maj. W. C. Gorgas and Dr. John 
Guiteras, at Las Animas Hospital, Cuba (see vol. Ill, p. 386, civil 
report of Gen. Wood, 1901): 

(1) Vergera; Spaniard. Infected by mosquitoes February 23, 
1901; recovered. 

(2) Carro; Spaniard. Inoculated bv infected mosquitoes August 8, 
1901; died. 

(3) Represas; Spaniard. Infected by mosquitoes August 8, 1901; 
recovered. 

(4) Campa; Spaniard. Infected by mosquitoes August 9, 1901; 
died. 

(5) Taylor, John R.; Englishman. Infected by mosquitoes August 
13, 1901; recovered. 

(6) Miss Clara Louise Maass, of East Orange, N. J., aged 25. 
Trained nurse in Las Animas Hospital. She served as trained nurse 
in Medical Department of the Army during the Spanish War. She 
volunteered and was bitten by infected mosquitoes August 14, and 
died of yellow fever August 18, 1901. 



30 YELLOW FEVER. 

(7) Varela; Spaniard. Infected by mosquitoes August 14, 1901; 
recovered. 

(8) Alonso; Spaniard. Infected by mosquitoes August 22, 1901; 
recovered. 

(9) Castillo; Spaniard. Infected by mosquitoes September 16, 
1901, by Dr. Carroll; recovered. 

(10) Semil; Spaniard. Infected by mosquitoes November 17, 
1901; recovered. 

The amount of the donations received by these volunteers is not 
known. 

There were 22 cases of experimental yellow fever produced by Reed, 
Carroll, and Lazear, and 10 in the experiments carried on in Habana 
by Gorgas and Guiteras. There were also 7 persons who underwent 
the very trying experiment of sleeping in infected bedding. 

It has been impracticable to make a complete list of the persons 
who submitted to the bites of mosquitoes but who failed to become 
infected, although it must be recognized that in many cases these 
exhibited as high a degree of courage as those who suffered an attack 
of yellow fever. 

It is hoped that the Senator will be able to obtain the consent of 
Congress to the erection of a monument which will be worthy of 
Maj. Reed, who conceived and carried out in so admirable a manner 
these epoch-making experiments, and to the assistants who shared in 
his labors and to the persons who offered their bodies for these dan- 
gerous experiments. 

Very respectfully, Geo. H. Torney, 

Surgeon General, United States Army. 

Hon. Robert L. Owen, 

United States Senator, Washington, D. C. 



[Senate Report No. 574, Sixty-first Congress, second session.] 

The Committee on Pensions, to whom was referred the. bill (S. 7252) granting an 
annuity to John R. Kissinger, have examined the same and report: 

A bill granting an increase of $125 per month to John R. Kissinger, the applicant 
herein, was favorably reported by your committee and incorporated in Senate bill 
6272 at this session and passed the Senate on February 15, 1910. 

The Senate report No. 210, which contains a very full statement of the services of 
this soldier and the grounds upon which his right to increase of pension is recognized, 
is as follows: 

S. 4479. John Kissinger, the claimant, was one of the bravest of soldiers who served 
in the Spanish-American War. For exhibition of moral courage his submission to 
inoculation of yellow fever seems unsurpassed. He is now a helpless paralytic, 
unable to walk, and he is totally disabled for any kind of employment, his ailment 
being myelitis, or disease of spine, and is the result of experiments made upon him 
when he volunteered to become a subject for experimental purposes in the yellow- 
fever hospital in Cuba. At the time he made the sacrifice he was a private in the 
Hospital Corps of the Army, in which he enlisted November 15, 1898. When he was 
finally discharged from the hospital, he was appointed an acting hospital steward and 
served as such until the date of his discharge, November 14, 1901. Previous to his 
enlistment he served in Company D, One hundred and fifty-seventh Indiana Volun- 
teer Infantry, from April 28, 1898, to November 1, 1898, having enlisted immediately 
at the breaking out of the war with Spain, and in response to President McKinley's 
call for troops. 

The commission that investigated the mosquito theory of transmission of yellow 
fever in the fall of 1900 was composed of Drs. Walter Reed, James Carroll, and Jesse 
W. Lazear. From a book entitled "Walter Reed and Yellow Fever," by Howard 
A. Kelly, professor of surgery of the Johns Hopkins University, published in New 



YELLOW FEVEE. 31 

York by McClure, Phillips & Co., on page 139, is the following paragraph in regard, 
to this soldier: 

''The subject of the first experiment was a young private from Ohio, named John 
R. Kissinger, who volunteered for the service, to use his own words, 'solely in the 
interest of humanity and the cause of science.' When it became known among the 
troops that subjects were needed for experimental purposes, Kissinger, in company 
with another young private named John J. Moran, also from Ohio, volunteered their 
services. Dr. Reed talked the matter over with them, explaining fully the danger 
and suffering involved in the experiment should it be successful, and then, seeing they 
were determined, he stated that a definite money compensation would be made them. 
Both young men declined to accept it, making it, indeed their sole stipulation that 
they should receive no pecuniary reward, whereupon Maj. Reed touched his cap, 
saying respectfully, 'Gentlemen, I salute you.' Reed's own words in his published 
account of the experiment on Kissinger are: 'In my opinion this exhibition of moral 
courage has. never been surpassed in the annals of the Army of the United States.'" 

Dr. Lazear died of yellow fever in Cuba at that time. Dr. Carroll died later of 
disease resulting from yellow fever contracted during his experiments with that 
trouble. Dr. Walter Reed is also dead, and the widows of these three men have all 
been remembered by the Government in an annuity of $125 per month. On account 
of the death of these doctors, soldier is unable, of course, to furnish any further evi- 
dence from them, but his volunteer submission to inoculation from infected mosqui- 
toes is a matter of record in the archives of the War Department. 

He is now receiving a pension of but $12 per month, and he can obtain no further 
relief because he is unable to furnish direct testimony tracing his present grievous 
condition back to yellow fever in the Army, although there is but little doubt that 
the relation of the cause and effect exists. Since his discharge he has never been in 
good health, which he at first attributed to slow recovery from that disease, thinking 
that with the passing of time his constitution would enable him to throw it off. He 
continued to fail, however, and is now a helpless paralytic. In the meantime he 
had married, and is now supported by his small pension and laundry work done by 
his wife and contributions to his support by a few people who appreciated his services 
to humanity. 

A bill to grant him a pension of $30 per month passed the House during the session 
of the Fifty-ninth Congress, but by mistake the rate was cut to $12 per month, at 
which amount it was finally approved. In his present helpless condition it is believed 
that he is entitled to a highly substantial measure of relief, his disability seemingly 
being due to causes of service origin. 

In view of the fact that a pension or annuity of $125 per month was granted to the 
widows of Drs. Lazear and Carroll, who conducted these experiments with yellow- 
fever infected mosquitoes, and who died as a result of being infected by mosquitoes, 
your committee are of the opinion that as great consideration should be given to the 
man who braved the danger and who, while he escaped with his life, is so helplessly 
crippled that he is unable to do anything to care for himself, as to the widows of Drs. 
Lazear and Carroll. Your committee therefore recommend in this case a pension 
or annuity of $125 per month. 

The bill went to the House and was referred to the Committee on Pensions. There 
the paragraph increasing the pension to the applicant herein was objected to as carry- 
ing a rate in excess of that allowed to any other private soldier and, regarded simply as 
a pension and without distinguishing language, establishing a vexing precedent. 

The facts in this case are exceptional and extraordinary. To meet the exceptional 
case and obviate the objections the pending bill recites the peculiar circumstances 
that distinguish the case and proposes an annuity of $125 per month, payable by the 
Secretary of War in the same manner as the same allowances are now paid to the 
widows of Drs. Carroll and Lazear. In view of the unprecedented facts in the case 
and the extraordianry services rendered by the soldier, your committee believe he 
should receive the same recognition accorded the widows heretofore mentioned. The 
bill is therefore reported back favorably with a recommendation that it pass. 



Chapter 5. 

IN MEMORIAM. 
DR. WALTER REED, MAJOR AND SURGEON, UNITED STATES ARMY. 

Whereas the Medical Society of the District of Columbia has sus- 
tained an irretrievable loss by the death of Walter Reed, who died 
at 2 p. m., November 23, 1902, from appendicitis, for which an oper- 
ation had been performed five days before: 

Be it resolved, 1 That in the death of Dr. Reed, the medical society 
has lost one of its most distinguished members, whose best efforts 
were always at its disposal and upon whom it had learned to rely as 
an able, calm, and accurate exponent of scientific medicine. 

Maj. Reed was born in Gloucester County, Va., September 13, 
1851, and was a graduate of the medical department of the University 
of Virginia, 1869, and Bellevue Hospital Medical College, 1872. He 
was appointed assistant surgeon, United States Army, June 26, 1875; 
promoted assistant surgeon, with the rank of captain, June 26, 1880; 
surgeon, with rank of major, December 4, 1893, and at the time of his 
death was first on the list of majors in the Medical Department. 

He served with distinction as medical officer at various Army 
posts in the Far West, and as his skill and devotion extended to both 
officers and enlisted men alike, he endeared himself to all classes in 
the command. 

During his service at Fort McHenry, Md., in 1881, and again while 
attending surgeon and examiner of recruits at Baltimore, from 
October, 1890, to October, 1891, he made special studies in bacteriology 
and pathology at the Johns Hopkins Hospital, and after a tour of 
service at Fort Snelling and St. Paul, he was selected by the Surgeon 
General, in August, 1893, as curator of the Army Medical Museum, 
where he continued his studies which ultimately secured for him fame 
and distinction. 

During the Spanish- American War he was president of the board 
of medical officers to investigate and report on the prevalence of 
typhoid fever in the Army, and the commission, strongly impressed 
with the agency of flies as carriers of this disease, recommended the 
collection of excreta in galvanized-iron tanks, which method was 
adopted and was followed by a cessation of the disease. 

His greatest achievement for science and humanity was his con- 
tribution to the cause, spread, and prevention of yellow fever. Start- 
ing from Finlay's theory of the agency of the mosquito in the dis- 
semination of this disease, the commission of which Dr. Reed was the 
head made a series of painstaking experiments and demonstrated 
conclusively the causal relation of Stegomyia fasciata to yellow fever 
epidemics and disproved the theory that the disease could be conveyed 
infomites, or that it was contagious in the ordinary acceptation of the 
term. 

1 The preamble and resolution were adopted December 3, 1902. 
32 



YELLOW FEVER. 33 

The practical value of this discovery, which in point of importance 
and far-reaching beneficence ranks only second to Jenner's discovery 
of vaccination, has been proved by the complete eradication of this 
scourge from Habana. 

Ma], Reed has demonstrated how to rid the world of yellow fever, 
but his studies as to the etiology of the disease were interrupted by 
his untimely death; he had, however, arrived at the conclusion that 
the disease was not due to Sanarelli's Bacillus icteroides, but was 
probably caused by some ultramicroscopic organism. Dr. Reed was 
a clear, forceful writer and speaker; all of his facts were collected with 
the utmost care and presented in a concise, logical, and convincing 
manner, and his crowning work shows the highest degree of scientific 
accuracy, combined with calm judgment and discrimination, qualities 
which are not only of the utmost importance in searching the causes 
of epidemic diseases and tracing their progress, but which would have 
also fitted him for the highest position in his corps. 

In every sphere of activity, whether as a medical officer, author, 
teacher, or investigator, he has acquired a distinction which rightly 
places him in the first rank of illustrious American physicians. 
His labors in behalf of science and humanity have been recognized 
by Harvard, Ann Arbor, and the American Medical Association, 
and he has borne his honors with accustomed modesty and innate 
dignity. Dr. Reed was singularly free from all mean self-interest 
and ambition, and was ever ready to give full credit to his col- 
leagues for their share of the work which made him famous. We 
have simply to recall his glowing tribute to that brave young soldier 
Kissinger, from Ohio, who on December 5, 1900, was the first to 
volunteer to be bitten by infected mosquitoes, with the only provision 
that he should receive no pecuniary reward, since as he expressed it, 
he was actuated "solely in the interest of humanity and the cause of 
science." Such exhibition of moral courage, in the opinion of Dr. 
Reed, has never been surpassed in the annals of the Army of the 
United States, and we will add, could never have been inspired except 
by a man of Dr. Reed's greatness. 

His lips are silent; no longer will the sound of his musical but 
decisive voice be heard within these walls, nor his personal mag- 
netism and discerning mind delight, instruct, and charm his listen- 
ers, but his deeds will live and his example will be an inspiration 
to the present and future generations. 

Dr. Reed's death in the prime of life, in the zenith of his dis- 
tinguished career, is a severe blow to scientific medicine, his corps, 
and the medical profession which he adorned. This society, while 
expressing the sincerest grief at the loss of our distinguished associate, 
whose personal qualities commanded our highest friendship and 
respect, is not unmindful of the irreparable loss sustained by his 
beloved family, to whom we beg to offer our heartfelt sympathy in 
the hour of their great affliction, united with the fervent hope that 
a grateful Nation will recognize the economic value of Dr. Reed's 
discovery and make adequate provision for those who were dependent 
upon him for support. 

Geo. M. Kober, 
D. K. Shute, 
. F. S. Nash, 

Committee. 
79965°— S. Doc. 822, 61-3 3 



34 YELLOW FEVER. 

Memorial meeting op the Medical Society of the District of Columbia, held 

December 31, 1902. 

introductory address by samuel s. adams, a. m., m. d., president. 

Ladies and gentlemen: Once more we have been called together 
to pay tribute to the memory of an honored colleague, whose counsel 
we have enjoyed for nearly a decade. The possessor of a striking 
personality, unusual reasoning power, an unbiased judgment, and a 
determination to enforce his convictions, Dr. Walter Reed could not 
fail to adorn and stimulate this scientific body as well as the military 
service of the United States Army. The aged die, and we wonder not, 
believing that they have fulfilled their mission; but when a colaborer 
in the prime of life, at the height of his usefulness, is cut down before 
he has had time to enjoy the full fruition of his labors, we marvel, 
we are lost in wonder. 

Dr. Reed was elected a "member by invitation " March 14, 1894. 
The preceding meeting, however, he made his first appearance in 
this society, having been invited to open the discussion on Dr. 
Kinyoun's paper, entitled "The prevention and control of diph- 
theria." In reverting to this debate, we can recall his modest 
demeanor, his convincing arguments, and his power to hold his audi- 
ence throughout a lengthy presentation of the subject. He began 
by saying that his clinical experience, laboratory work in inoculating 
animals, and bacteriological studies had led him to certain ideas as 
fixed convictions : 

1. The Klebs-Loeffler bacillus is usually characterized by a deposit 
of false membrane in the throat and is attended by frequent fatal 
sequelae. This bacillus he believed to be the cause of true primary 
diphtheria. 

2. That diphtheria is local in the beginning and by the production 
of virulent toxins tends to become rapidly constitutional. The bacilli 
themselves have been found in the internal organs of the human 
subject, as well as in those of animals. So that we can not any longer 
say that the bacilli remain local throughout the attack. 

3. Diphtheria is not spread by water and food, except by milk 
and its products, which are infected in transitu. He strongly advo- 
cated the bacteriological examination in making the diagnosis. 

Two months later, in discussing tuberculosis, he dwelt upon these 
two points: "The possibility of the transference of tuberculosis by 
vaccination; and the possibility of its transference from mother to 
child in utero." 

January 9, 1895, in discussing diphtheria and its treatment by its 
antitoxin, he said he believed the production of antitoxin should be 
under municipal control and be tested by disinterested parties so as to 
avoid imposition by unscrupulous men whose desire is gain. He 
lived to see the enactment of a law to protect this community from 
spurious viruses. He had witnessed the wonderful immunizing 
effects of antitoxin, so advised its use as a preventive as well as a 
curative agent. 

His masterly hand struck the death blow to the opponents of anti- 
toxin in the discussion of ' ' The clinical aspects of diphtheria treated 
by its antitoxin," December 4, 1895. 

A clinician of wide experience and recognized ability, while dis- 
claiming any unfriendliness toward its use, had taken a decided stand 



YELLOW FEVER. 35 

against this serum, basing his remarks upon the statistics and argu- 
ments of a distinguished English laryngologist and a well-known 
American pediatrist. It seemed as if the pendulum were swinging 
toward the opposition when Walter Reed entered the forum — majes- 
tic, fearless, determined to conquer. With keen eyes fixed on his 
principal antagonist, he hurled his weapon of defense in unmistakable 
language, when he said: 

You are theorizing while we are dealing with facts. If another friend of antitoxin 

arises and deals it such blows as Dr. has given it, the antitoxin serum will be 

slaughtered in the house of its friends. 

In concluding his remarks, came this appeal: 

I myself almost feel like saying, with the reader of the paper, that the failure to use 
it in a case of human diphtheria is criminal; and I beg of you, that if you have not yet 
done so, when you next stand by the bedside ofyour patient afflicted with this disease, 
you do not, through any fear of its peculiar action, withhold this invaluable remedy. 

It must have been a great satisfaction to him to witness not only 
the conversion of his opponents, but the universal use of the anti- 
toxin of diphtheria. 

His paper entitled "What credence should be given to the state- 
ments of those who claim to furnish vaccine lymph free from bac- 
teria?" is worthy of praise. He conducted a series of experiments 
upon monkeys by vaccinating them with various vaccine matter, 
and was " convinced that all virus contained bacteria and that 
bacteria-free lymph did not exist." 

It is a singular coincidence that the last appearance of Dr. Reed 
in this society was at a memorial meeting, when he eulogized as 
an author his friend and associate, Dr. W. W. Johnston. 

The Medical Society of the District of Columbia is proud of hav- 
ing had the friendship of Walter Reed; we gloried in his achievements, 
and we now mourn the loss of a courteous, industrious, famous, and 
highly honored member. 

HISTORICAL REMARKS, BY MEDICAL DIRECTOR R. A. MARMION, UNITED STATES NAVY. 

Mr. President and members of the Medical Society of the District 
of Columbia: Walter Reed was born in Gloucester County, Va., on 
the 13th of September, 1851, and was the son of Rev. Lemuel 
Sutton Reed, who was for 40 years or more an eminent Methodist 
minister. In his personal appearance Walter was highly favored 
even in his youth, and to this there were added a gentleness of dis- 
position and a graciousness of manner which won for him the admira- 
tion of all who were brought in contact with him — qualities which we 
know were characteristic of him ever after. Intellectually he was, 
as a boy, precocious and devoted to study, so that at the age of 15 
he had acquired a knowledge of Latin and Greek rarely found in one 
so young. History, literature, and philosophy were also favorite 
studies, and his familiarity with them rendered him the peer of many 
who were his seniors in age by several years. 

By a special dispensation he was matriculated in the academic de- 
partment of the University of Virginia at the age of 16. He quickly 
attained and held, throughout that first year, the highest standing in 
his classes. Owing, however, to the limited means of his father, who 
was maintaining two other sons at the same school, it became evident 
to Walter that he would not be able to carry out his original plan of 
completing the academic course; so, at the beginning of the following 



36 YELLOW FEVEK. 

year he began the study of medicine, and at the end of one session of 
nine months he was awarded the degree of doctor of medicine, although 
he was not yet 18 years of age. This feat he accomplished in spite 
of the advice of friends who had, in advance, sought to dissuade him 
from undertaking it. His only reply to such advisers was that "he 
did not fear the result." In a few months after his graduation at the 
University of Virginia he went to New York and matriculated at the 
Bellevue Medical College, and in one session acquired the degree of 
M. D. Following his graduation at Bellevue he was attached to 
various hospitals in New York and Brooklyn, conspicuously the 
Brooklyn City Hospital and the Charity Hospital on BlackwelFs 
Island ; at the latter he devoted himself especially to the study of the 
diseases of women and children. He was also for awhile, one of the 
physicians to the poor of New York City. During his Brooklyn life 
he had attracted the attention of Dr. Joseph Hutchinson, one of the 
most prominent medical men of that city, who urged and secured his 
appointment as one of the five inspectors of the board of health — a 
position much sought after in those days. This post he was filling 
most creditably when his twenty-first birthday dawned. Even at 
this early date, Dr. Keed had acquired a very enviable standing 
among the medical men of New York and Brooklyn, among whom 
he was especially well known for his skill as a surgeon. Within a few 
years, as we have seen, he had been holding various professional posi- 
tions of responsibility, but he could not help feeling that there was a 
point beyond which he could not go on the road toward that success 
which he coveted, without the influence of wealthy friends and of in- 
fluential social connections on the spot. Thus it was that in 1874 he 
began to think seriously of entering the Medical Corps of the Army or 
of the Navy, and, by the spring of 1875, he had chosen the Army as 
the field of his future labors. 

I can not dismiss this part of my subject without pausing for a 
moment to weigh certain characteristics of our lamented colleague 
and, first of all, I would advert to the fact that even in his boy- 
hood years there shone forth so many of the splendid traits which 
illustrated his after life; he was fired with ambition and sustained 
by an indomitable energy in his early student days which invari- 
ably brought him victory; but his innate tenderness of nature and 
his exquisite regard for the sensibilities of a disappointed contestant 
so dominated him at such times that no one ever knew him to boast 
of his victory. A deference for the opinions of others, too, was always 
a prominent characteristic; and this we have seen evinced so uni- 
formly in the discussions taking place at meetings of this society. 
And so I might go on analyzing and dwelling upon other traits, 
but the limited time prevents me. 

Turning to the military history of Maj. Walter Reed, as borne 
upon the records of the office of the Surgeon General of the Army, 
we find that he was appointed assistant surgeon with the rank of 
first lieutenant June 26, 1875; promoted to be assistant surgeon 
with the rank of captain June 26, 1880; surgeon with rank of major 
December 4, 1893; and at the time of his death was first on the list 
of majors in the Medical Department. 

He was on duty in the Department of the East from July 23, 1875, 
to May 21, 1876; in the Department of Arizona from June, 1876, to 
May, 1880; again in the Department of the East from September, 



YELLOW FEVER. 37 

1880, to November, 1882. From November, 1882, to July, 1887, 
he was attached to the Department of the Platte, and from August, 
1887, to October, 1890, he was on duty at Mount Vernon Barracks, 
Ala. His next assignment was to duty in Baltimore, Md., from 
October, 1890, to October 1891, when he was transferred to the De- 
partment of Dakota, where he remained until August, 1893, when he 
was ordered to duty in the office of the Surgeon General of the Army. 
Under this assignment he was curator of the Army Medical Museum 
and member of the faculty of the Army Medical School for over nine 
years and up to the date of his death, which occurred in this city 
November 23, 1902. 

In the meantime, too, he served, at several different periods, as 
member of the Army Medical Board in this city, was a member 
of the cholera board in July, 1898; was on detached duty making 
inspections of camps and field hospitals in August, 1898; was member 
of the typhoid fever board in August, September, and October, 1898; 
in October, 1898, he was on inspection duty at Natural Bridge, Va., 
and again in April and May, 1899, at Puerto Principe, Cuba. In 
March and April, 1900, he was ordered to investigate and report 
upon the use of electrozone and germicides at Tampa and Habana, 
and in June and Jul}', 1900, was a member of a board of medical 
officers at Camp Columbia, Cuba, for the purpose of scientific 
investigation with reference to infectious diseases prevalent in Cuba, 
and, from September 27 to October 13, 1900, on similar duty with 
regard to yellow fever. These various assignments were of great 
importance from the standpoint of preventive medicine and did 
much to solidify the foundation on which he was destined to erect 
the structure "more lasting than brass" which to-day towers above 
the many works of a life full of labors for the benefit of his fellow 
man. 

It seems to me that I can not better close this paper than by 
quoting the language of the official record of Maj. Reed as drawn 
from the files of the Surgeon General's Office: 

Of Maj. Reed's work in the Medical Department and his scientific researches, it 
is probable a complete history can never be obtained. His eminence as a bacteri- 
ologist, and in practical hygiene as applied to military life (as a student of all forms of 
bacteria) led to his being intrusted with special investigations, which were interrrupted 
by his death, and which, it is now believed, will never be completed. He was 
regarded by his associates as a man who combined an unusual degree of scientific 
accuracy with calm judgment, which rendered him invaluable in searching out the 
causes of epidemic diseases and tracing their progress. 

In 1901 he began the investigation of the cause and the prevalence of yellow fever, 
conducting his investigations at Quemados, near Habana, where he established 
headquarters and was given every facility for conducting his experiments. 

The conditions in Cuba in 1901 were such as made the investigations of Maj . Reed 
and his corps of assistants of special moment. An epidemic of yellow fever existed 
despite the efforts of the sanitary experts, led by Gen. Wood, who were endeavoring 
to stamp out the disease. The houses of persons infected were subjected to rigid 
disinfection. Furniture was destroyed and every possible precaution was taken to 
prevent the spread of the disease under the old treatment. Maj. Reed became con- 
vinced that proper sanitation was not all that was needed. He believed that some 
other agency than accumulations of filth was responsible for the spread of the disease, 
and his attention was attracted to the fact that it took much longer for a house to 
become infected than the usual time of incubation. This suggested a biting insect 
as an intermediate host of the parasite, and he asked and promptly received from 
Gen. Wood permission to make experiments with mosquitoes as the conveyers of 
yellow fever, and a liberal supply of money for these experiments. It was thus 
determined beyond question that through a certain species of mosquito the yellow 
fever germ was disseminated. 



38 YELLOW FEVER. 

In recognition of this precious work the degree of master of arts 
was conferred upon Maj. Reed by the Harvard University in June, 
1902, because, as President Eliot stated when the degree was awarded, 
Maj. Reed had demonstrated how to rid the world of yellow fever. 
About the same time the degree of LL. D. was conferred upon him 
by the University of Michigan at Ann Arbor, Mich. 

MAJ. REED AS A MEDICAL OFFICER, BY MAJ. J. R. KEAN, SURGEON, UNITED STATES 

ARMY. 

In speaking of Dr. Reed as a medical officer we should consider 
especially that part of his career with which the members of this 
society are least familiar, namely, from his entrance into the Army 
in 1875 to his assignment to duty in Washington in 1893. With 
the latter date began his career as a scientific man, although much 
of his time during this last decade was given to examining boards 
and other work of a military rather than scientific character, and the 
race horse spent much time at the plow. 

These 18 years of garrison duty were, we may be sure, not wasted, 
yet the official records tell but little of them. The records show 15 
changes of station (with 4 years in Arizona, 5 in the Department of 
the Platte, 2 in the Department of Dakota, 3 in the South, and 3 in 
the East). There are a few brief commendations for professional zeal 
and devotion to his patients, and that is all. 

The work of young Army surgeons claims always little space in the 
gazettes or in the reports of military commanders, and in the seventies 
and eighties the life was certainly not stimulating to intellectual 
effort. 

The surgeon shared with his comrades of the line the tedium of 
long marches and the monotonous sameness of Arizona summers and 
Dakota winters. And those with whom bonne camaraderie out- 
weighed studious industry shared also the afternoons of bottlepool 
and beer and the nightly seductions of draw poker. But for medical 
officers this life was redeemed by the study of our profession, which 
was then beginning to broaden out from ancient channels into the 
full flood of recent progress, and it was saved from triviality by those 
stern responsibilities of life and death which practice brings to all 

Ehysicians. . To lesser minds the limitations of such a life might have 
een narrowing, but for the eager industry and professional devotion 
of a Reed they made the roots strike deep ; and when we are surprised 
at the rapid growth and splendid fruit of his career as a scientist we 
must remember that in the post surgeon's unmarked life the seed was 
germinated and the roots were firmly set. But for the opportunities 
given him by his position in the Army, however distinguished he may 
have become in other ways, it is safe to say that the work with which 
his fame will always be inseparably connected would never have 
been accomplished by him. During this long apprenticeship _ he 
acquired too that perfect familiarity with the conditions and limita- 
tions of Army life which, combined with his scientific knowledge and 
sound judgment, made him the best sanitary inspector in the Army 
and the court of last resort on all sanitary questions. 

I first learned to know Dr. Reed by reputation when in the spring 
of 1888 I followed him in station at Fort Robinson, a two-battalion 
post in the northwest corner of Nebraska. I learned much of his 
devotion to his patients, and their devotion to him was equally 



YELLOW FEVER. 39 

in evidence. The country about is thinly settled with families 
locally known as "Grangers/' who were attempting to support 
themselves by farming in a grazing country where the rainfall was 
not sufficient for good crops except only about one year in three. 
The crop of babies, however, never failed, and the Klebs-Loeffler 
bacillus and the pneumococcus flourished perennially in their wretched 
cabins. To Reed's tender and generous spirit the call of these poor 
people never came in vain, and the trail was never so long or the 
night so dark as to deter him. In the winter these rides were really 
dangerous and a source of much uneasiness to his family and friends 
for fear of his being overtaken by one of those blizzards in which 
the staunchest horse turns tail to the wind and the most experienced 
frontiersman can not see his way, and the danger to the lost traveler 
is greater than that of a battle. 

Again we find him at Mount Vernon Barracks in Alabama, accord- 
ing to the official statement of his commanding officer, devoting 
himself with the same earnestness and patience to the sick of Geroni- 
mo's band of Apaches, then held there as prisoners, and to the sick 
negroes of the surrounding country, as to his own patients in the 
garrison. 

Of the first years of his service which he spent in Arizona I gained 
some knowledge when in the summer of 1896 he came to Key West, 
my station at that time, to study the blood of variola — there being 
an epidemic of smallpox there at that time. All day he would 
sit over his microscope, but the evenings we spent on the coolest 
corner of the porch looking out at the quiet tropical sea, while he 
told reminiscences, suggested, it may be, by the heat, of his service 
at Fort Yuma and Camp Apache. These stories were full of that 
humor which was so characteristic and so pleasing a trait of his 
daily conversation, and some of these were models of the short 
story. The history of Sally Ann, a Gila monster (named after the 
two ladies of the post most conspicuous in church work), which the 
chaplain captured in his kitchen, and undertook to tame, would 
have made a perfect magazine article just as Reed told it. His 
account of his summer at Yuma, the hottest of Army posts, where 
the daily July maximum was from 112° to 115°, still brings back a 
clear-cut picture to my memory, and I can see him with his messmate, 
a captain of infantry, who weighed 250 pounds, and the soldier — or 
in Army parlance "striker" — who filled the dual role of chef and 
butler. The captain, a vertiable Porthos, sat down to dinner in 
two garments, with a fan, a towel to wipe his face, and near at hand 
a pitcher of the largest size full of water from the olla, for there 
was no ice. Before him was a large roast of range beef, which, 
after helping Reed, he would consume entirely and likewise empty 
the water pitcher. 

On one occasion Reed took a leave, and, in company with another 
officer and a lady of the garrison going home, drove in an ambulance 
150 miles to the railroad. The other officer was charged with the 
commission of laying in the food for this trip of nearly a week. After 
they started they found that the provision consisted simply of crack- 
ers and sardines. Reed up to that time had never been able to eat 
sardines, but he learned on this trip. He had his share also of Indian 
campaigning, and on one occasion brought into the post a little Indian 
girl of 4 or 5, who had been so horribly burned that her people had 



40 YELLOW FEVER. 

abandoned her to die. This child he succeeded in saving and brought 
her up in his family as a nurse for his children in spite of the warning 
of that keen old Indian fighter, Gen. Crook. When she was grown, 
the savage Apache blood asserted itself, and she ran away, after 
giving evidence that 15 years of gentleness and refinement had not 
modified the cruel and deceitful character of her race. 

Memory often holds most fast to trivial things, but they are 
usually characteristic. So, though what has come into my mind to 
tell you of our dead friend is not of weighty matters; yet they show 
the odd vicissitudes of Army life and show him as he was — the 
pleasant comrade, the eager student, and the devoted doctor, gentle, 
unselfish, modest, and brave, as the gentle and devoted ever are. 
Over this earnest spirit and the high purposes of his life played always 
a merry and kindly humor like the dancing lights and reflections from 
the surface of a deep, swift river. It was often keen, but never bitter, 
and was his most striking social characteristic, as was devotion to the 
duty which was before him the dominant feature of his professional 
life. For him, as for the great Duke — 

The path of duty was the way to glory. 

He that walks it only thirsting 

For the truth, and learns to deaden 

Love of self, before his journey closes 

He shall find the stubborn thistle bursting 

Into glossy purples, which outredden 

All voluptuous garden roses. 

He that ever follows her commands 

On with toil of heart and knees and hands 

Through the long gorge to the far light, has won 

His path upward and prevailed, 

Shall find the toppling crags of duty scaled 

Are close upon the shining table-lands, 

To which our God Himself is moon and sun. 

Such was he — his work is done. 

DR. WALTER REED AS A TEACHER, BY A. F. A. KING, A. M., M. D. 

At the time of the organization of the United States Army Medical 
School, in 1893, Dr. Reed was appointed professor of bacteriology 
and clinical microscopy, and he continued to fill this position and 
to perform its duties most acceptably until the time of his decease., 
in November, 1902. 

Two years after beginning his work in the Army Medical School 
he was elected professor of pathology and bacteriology in the medical 
school of the Columbian University in this city, and he continued to 
hold this position also until the end of his life. 

If we endeavor to ascertain in a general way what are the require- 
ments necessary for anyone to become a really skilled and successful 
instructor in any department of knowledge, and then ask ourselves 
how far Prof. Reed possessed these qualifications, it will at once be 
seen that the particular attributes necessary were preeminently his 
own. 

To teach well one must know well the subject to be taught, and, 
conversely, he who can not explain a thing clearly to somebody else 
does not usually know it well himself. 

In the whole domain of medical science there is probably no 
subject more difficult and intricate than that of pathology, especially 



YELLOW FEVER. 41 

when considered in relation with bacteriology, this latter being also 
a comparatively new departure, and therefore bristling with the 
unfamiliar terms of a new and labored nomenclature, as every new 
science necessarily must be. 

Notwithstanding these difficulties, Prof. Reed, with his well- 
trained mind and cultivated powers of observation, inspired, too, with 
the spirit of research and led on by the charm of discovering new 
principles and new facts, had devoted himself with so much ardor, 
earnestness, and industry to the study of his chosen sphere of thought 
that, it may be said, all difficulties had been trampled under his feet; 
that he rose, step by step, to higher and still higher planes of knowl- 
edge, until reaching an eminence where the whole subject became 
easily intelligible in one comprehensive view and where he himself 
attained a complete mastery of his favorite theme. 

Having traversed the highways of knowledge himself he was 
fully able to lead his pupils along the same paths and perhaps point 
out to them many short cuts which were easier than the longer 
distances and more laborious journeys originally pursued by him- 
self. It should be remembered also that many of these roads were 
not always the well-traveled avenues of old lines of thought, but, on 
the contrary, entirely new, strange, and perhaps lonely ways, far out 
in the prairies of investigation, where briars of speculation, weeds 
of error, and the ignes fatui of false theories were liable to obstruct 
and mislead the honest seeker for truth. It was under these circum- 
stances that Prof. Reed became a trusted guide and counselor. In 
these trackless wastes of thought he could not easily get lost or take 
a wrong direction, for in many instances he was able to say: "I made 
these paths myself," and he well knew whither they would lead. 

The successful teacher, however, must not only possess the requi- 
site knowledge and be able to guide his pupils in the best way, and 
hold out to them the easiest method of obtaining the information for 
which they are in search, but he should also have the faculty of pre- 
senting the subject in such a manner as to hold their undivided 
interest and attention by pointing out the attractive features and 
pleasing aspects of the subject under discussion. Dreary, indeed, 
would be the road to learning were it always through thorns, thistles, 
and briars, with no flowers to charm and no vistas in the forest 
through which we might at times obtain a glimpse of pleasant scenes — 
of sunshine and beauty. Dreary, and dull too, will be the teacher 
who continues his endless monotony of tiresome propositions, with 
no touch of humor and no sparkle of wit to vary the irksomeness of 
continued effort and awaken the flagging power of a strained atten- 
tion by the pleasant diversion of an occasional happy thought. 

In this particular again Dr. Reed was singularly fortunate. One 
of his latest admiring pupils writes me that — 

his lectures, besides satisfying the zealous seeker for knowledge, were spiced with 
humor which was most refreshing, and which made the relation between himself 
and his students a freer and more sympathetic one. — Donnally. 

Indeed, in whatever aspect we review Dr. Reed's work as a teacher 
and however critically we single out the several qualifications required 
for the best and most successful execution of the teaching art, we 
find Prof. Reed happily endowed in a more than usual degree with 
these special gifts and qualifications, and which he knew full well 
how to utilize to the best advantage. 



42 YELLOW FEVER. 

During the later years of Prof. Reed's work in the medical school 
of the Columbian University he was assisted by Dr. James Carroll, of 
the United States Army, who also accompanied Dr. Reed to Habana, 
and again assisted him in their well-known experiments with mos- 
quitoes and yellow fever. No one, perhaps, was better acquainted 
with Dr. Reed's methods of teaching than Dr. Carroll, who kindly 
writes me as follows : 

Dr. Walter Reed was respected and beloved by all his pupils. Always kind and 
courteous, earnest and enthusiastic, he imbued them with the same spirit, and invari- 
ably commanded their respect and attention. A thorough master of his subject and 
of the English language, he treated the driest and most difficult topics in such a man- 
ner as to render them lucid and interesting. His marvelous accuracy and clear con- 
ception of every detail, his charming personality and polished manner, made him an 
ideal professor, of whom his students were both fond and proud. Of nervous tempera- 
ment, he was quick to note and resent the slightest laxity and inattention; and when 
it became necessary to administer a rebuke it was implied rather than given directly, 
his delicacy of feeling prompting him to soften the blow by a subtle flash of wit that 
convulsed the class and diverted attention from the culprit. The lesson was never 
forgotten by him for whom it was intended, and it was never necessary to repeat it, 
for the moral effect of the slightest manifestation of his displeasure was far greater than 
could have been the dread of any other method of reproof. So closely was he in sym- 
pathy with his class and so securely had he engrafted himself upon their affections that 
their inquiries during his illness and manifestations of grief upon his demise indicated 
the loss of a dear friend, guide, and counselor rather than a teacher of cold scientific 
facts. 

Another pupil, Capt. J. Hamilton Stone, assistant surgeon, United 
States Army, writes me as follows : 

As a teacher Dr. Reed always seemed to me to be, first of all, master of his theme. 
His information was so much his own — a part of him, as it were — that when it was 
given to others it flowed forth with unadulterated naturalness, and sparkled with a 
keen interest which his charming personality could not help but lend it. These 
qualities would not permit his words to fall upon deaf ears. His kindly and consid- 
erate mien, together with his universally acknowledged high scientific attainments, 
won for him both the respect and admiration of his students. His language was always 
interesting, eloquent, and well appointed. When at his best his voice would reach a 
high falsetto note, and this was his characteristic method of impressing important facts 
upon dull or indurate intellects. His students never feared him, but from the start 
regarded him with filial affection . Of patience, that special attribute of a good teacher, 
he possessed an abundance. He was constantly at the side of his pupil in the lab- 
oratory, advising, consoling, encouraging, and, above all, instructing. 

A student of the Columbian University, Mr. H. H. Donnally, 
remarks that — 

Dr. Reed's lectures were models of order and system. A recital of the various views 
previously held in the different branches of pathology and bacteriology always led up 
to and served to emphasize the more recent and generally accepted theories. In these 
historic reviews the student was constantly surprised at Dr. Reed's remarkable 
memory for dates and his familiarity with the host of investigators and their several 
special lines of research, not only those in this country, but others in all parts of the 
civilized world. This method of unfolding the subject historically, with a final and 
forcible exposition of the latest current views, was keenly appreciated by the students 
and gave them a broad and comprehensive picture of the whole subject, which was 
easily remembered and understood. 

Finally, I must express my great regret that it has seldom fallen 
to my lot to hear Dr. Reed lecture, and I have never witnessed his 
demonstrations in the laboratory; hence I have supplemented my 
own remarks by quoting from others who had happily been more 
favored in these respects, and certainly no statements of mine could 
more appropriately represent the work of Prof. Reed as a teacher 
than these eloquent expressions from his own faithful and loving 
pupils. 



YELLOW FEVER. 43 

DR. WALTER REED AS AN AUTHOR, BY CH. WARDELL STILES, PH. D., ZOOLOGIST, 
UNITED STATES PUBLIC HEALTH AND MARINE-HOSPITAL SERVICE. 

Zoology was once facetiously defined as "The study of the useless." 
This definition will doubtless appeal to many people as quite appli- 
cable; for to persons not in scientific work the practical application 
of long, detailed, and often tedious accounts of animals is not always 
evident. In defending such work, many men quote the time-honored 
expression "Knowledge for knowledge's sake." But seeing little 
difference in principle between this expression and the phrase ' l Money 
for money's sake," and not wishing to pose as a defender of the 
intellectual miser, I take great pleasure as a professional zoologist in 
acknowledging the debt which zoology owes to the medical profession 
for the practical application of zoologic knowledge to the benefit of 
mankind. 

Zoologists have shown how important the insects are from an 
economic standpoint in making or destroying certain foods upon 
which we directly or indirectly depend for life. But it is chiefly to 
the medical profession that this world is indebted for the application 
of entomologic knowledge in connection with the transmission of the 
important infectious diseases, hence in connection with saving life. 

Dr. Walter Reed, in 'whose memory we meet here this evening, 
stands out among medical authors as one who has been particu- 
larly prominent in this field of work, and though he was not a zoolo- 
gist by training, his writings in applied zoology in connection with 
yellow fever entitle him to rank as among the greatest of applied 
zoologists. 

It was the United States Bureau of Animal Industry which first 
clearly demonstrated the great importance of arthropods as interme- 
diate hosts of epidemic diseases, and its reports on the tick (Boophi- 
lus) as a transmitter of Texas fever of cattle will always remain classic. 
Then the writings of two English physicians, Ross and Manson, 
and of an Italian zoologist, Grassi, carried the subject further in 
connection with mosquitoes and malaria. 

Finally, the writings of our friend Walter Reed and of his asso- 
ciates demonstrated to us the relation of mosquitoes and yellow 
fever and showed us how we could protect both life and commerce 
from this scourge. 

It is interesting to note that all three of these discoveries in applied 
zoology show certain parallels. All deal with diseases which are 
preeminently tropical or subtropical; all deal with diseases of 
unusual economic importance; and the actual positive experimental 
work upon transmission has been done chiefly by English-speaking 
investigators. 

Might I add here, without misinterpretation, that the Texas fever 
work was done before the days of the Noble prize. The first medical 
awards of this prize of $40,000 were to Behring in recognition of 
his work for mankind in connection with diphtheria, and to Pawlow 
for his work in physiology ; the next award was to Ross in recognition 
of his work for humanity in connection with malaria. Are not Reed, 
Carroll, Lazear, and Agramonte the natural candidates for the next 
award because of their work for mankind in connection with yellow 
fever, and in case the conditions of the grant permit it, should not 
each of the widows of two of these men receive the share which 
would have gone to her husband ? 



44 YELLOW FEVER. 

Our friend, Dr. Reed, was not what would be called a prolific 
writer. His numerous routine duties prevented him from furnish- 
ing the manuscript which we had a right to expect from a man of 
his ability. Still, beside short remarks in society discussions, his 
bibliography contains 27 original articles all printed between 1892 
and 1902. Ten of these articles dealt with yellow fever, three or 
four with typhoid, two each with malaria and erysipelas, and one 
each with cholera, pneumonia, trikresol, vaccine, artificial immunity 
against vaccination, amoeboid bodies in the blood of vaccinated 
monkeys and children and in variola, formaldehyde, splenic leukemia, 
and electro zone. All were in English, and although they were all 
official Government work, it is a striking fact that only five, so far 
as I have been able to find, were published by the Government. 

Regarding the general style of the articles, there are three points 
in particular which are striking: First, the attention given to details 
immediately reminds us of the writings of Dr. Theobald Smith of 
Harvard University; second, the directness of diction immediately 
reminds us of Dr. J. McKeen Cattell, professor of experimental 
psychology, Columbia University. In fact, one of the characteristics 
for which Dr. Reed was noted among his friends was the absolutely 
straight line of his thoughts and the orderly, lucid, and logical devel- 
opment of his subject. Third, Dr. Reed was of a judicial tempera- 
ment, and the judicial manner in which he handled his subject, even 
in controversy, forcibly reminds us of the same prominent character- 
istic in Prof. William H. Welch of Johns Hopkins University. 

In forecasting the time of the influence of Dr. Reed's writings, it is 
clear that his articles on yellow fever will far outlive his papers on 
other subjects. His other writings will be known to men only in 
certain lines of medical work, but his papers on yellow fever will be 
known directly or indirectly to both physicians and zoologists, and to 
both professional men and business men. They will be quoted for 
decades to come, both by Government officials and by private practi- 
tioners, and they will be one of the most important factors in deter- 
mining the future policy of civilized nations in dealing with yellow 
fever, a disease which we dreaded only a few years ago, but now one 
which, thanks to the work of Reed and his colleagues, will soon be 
little more than a medical curiosity. 

Bibliography, 
reed, walter. [1851-1902.] 

1892. — The contagiousness of erysipelas. Boston M. & S. J., v. 126 (10), March 10, 
p. 237. 

1893. — Remarks on the cholera spirillum. [An address before Ramsey County 
Medical Society, March 28.] Northwest. Lancet, St. Paul (297), v. 13 (9), May 1, 
pp. 161-164. 

1894a. — Association of Proteus vulgaris with Diplococcus lanceolatus in a case of 
croupous pneumonia. Johns Hopkins Hosp. Bull., Baltimore, v. 5 (34), March, pp. 
24-25. 

1894b.— The germicidal value of trikresol. St. Louis M. & S. J. (642), v. 66 (6), 
June, pp. 329-337. 

1894c— Idem. Proc. Ass. Mil. Surg. U. S. (Washington), St. Louis, v. 4, pp. 199- 
208. 

1894d. — A brief contribution to the identification of Streptococcus erysipelatos. 
Boston M. & S. J., v. 131 (14), October 4, pp. 339-340. 

1895a. — An investigation into the so-called lymphoid nodules of the liver in typhoid 
fever. Johns Hopkins Hosp. Rep., Baltimore, v. 5, pp. 379-396. 



YELLOW FEVER. 45 

1895b. — An investigation into the so-called lymphoid nodules of the liver in ab- 
dominal typhus. Am. J. M. Sc., Philadelphia, n. s., v. 110, pp. 543-559. 

1895c. — What credence should be given to the statements of those who claim to 
furnish vaccine lymph free of bacteria? [Read before the District of Columbia Med. 
Soc, June 5.] J. Pract. M., N. Y., v. 5 (12), July, pp. 532-534. 

1896a.— [The character, prevalence, and probable causation of the malarial fevers 
at Washington Barracks and Fort Myer.] Rep. Surg. Gen. Army, Wash., pp. 65-77, 
1 diagram, 1 table. 

1896b.— The parasite of malaria. J. Pract. M., N. Y., v. 6 (9), Apr;, pp. 382-383. 

1897a. — Serum diagnosis in typhoid fever. Rep. Surg. Gen. Army, Wash., pp. 
68-73. 

1897b. — On the appearance of certain amoeboid bodies in the blood of vaccinated 
monkeys (Rhoesus) and children, and in the blood of variola. An experimental study. 
Tr. Ass. Am. Physicians, Phila., v. 12, pp. 291-302, 2 pis. _ 

1897c. — On the appearance of certain amoeboid bodies in the blood of vaccinated 
monkeys (Rhoesus) and children, and in the blood from cases of variola. An experi- 
mentalstudy. J. Exper. M., N. Y., y. 2 (5), Sept., pp. 515-527, pis. 38-40. 

1897d. — Typhoid fever in the District of Columbia; diagnosis: The value of Widal's 
test, the dried blood method. Nat. M. Rev., Wash., v. 7 (6), Nov., pp. 144-146. 

1897e. — [Experiments with Hollister's formaldehyde generator.] Rep. Surg. Gen. 
Army, Wash., pp. 103-104. 

1898.— Splenic leukaemia, [Trans. Med. Soc. District of Columbia, Oct. 27, 1897.] 
Nat. M. Rev., Wash., v. 7 (9),Feb., pp. 265-266. 

1900. — Report on the practical use of electrozone as a disinfectant in the city of 
Havana, Cuba. Rep. Surg. Gen. Army, Wash., pp. 178-186. [MS., dated Apr. 20.] 

1901a. — The propagation of yellow fever; observations based on recent researches. 
[Address before 103d Ann. Meeting Med. and Chir. Fac, Stateof Md., Bait., Ap. 24-27.] 
Med. Rec, N. Y. (1605), v. 60 (6), Aug. 10, pp. 201-209, tables 1, 2. 

1901b.— Idem. Rep. Surg. Gen. Army, Wash., pp. 187-202, 1 pi., 6 fever charts. 

1902. — Recent researches concerning the etiology, propagation, and prevention of 
yellow fever, by the United States Army Commission. J. Hyg., Cambridge, Eng., 
v. 2 (2), Apr. 1, pp. 101-119, charts 1-3. 

REED, WALTER, AND CARROLL, JAMES. 

1899a. — Bacillus icteroides and Bacillus cholerae suis. A preliminary note. Med. 
News, N. Y., v. 74 (17), Apr. 29, pp. 513-514. 

1899b. — The specific cause of yellow fever. A reply to Dr. G. Sanarelli. Med. 
News, N. Y., v. 75 (11), Sept. 9, pp. 321-329. 

1900. — A comparative study of the biological characters and pathogenesis of Bacillus 
X (Sternberg), Bacillus icteroides (Sanarelli), and the hog-cholera bacillus (Salmon 
and Smith). [Received for publication Feb. 25.] J. Exper. M. [Bait.], v. 5 (3), 
Dec. 15, pp. 215-270, figs, a-o, pi. 19, figs. 1-3. 

1901. — The prevention of yellow fever. [Read at 29th Ann. Meeting, Am. Pub. 
Health Ass., Buffalo, Sept. 16-21.] Med. Rec, N. Y. (1616), v. 60 (17), Oct. 26, 
pp. 641-649, figs. 1-10. 

1902. — The etiology of yellow fever. A supplemental note. [Read at 3d Ann. 
Meeting, Soc. Am. Bacteriologists, Chicago, Dec. 31, 1901, and Jan. 1, 1902.] Am. 
Med., Phila., v. 3 (8), Feb. 22, pp. 301-305, charts 1-6. 

REED, WALTER; CARROLL, JAMES; AND AGEAMONTE, ARISTIDES. 

1901a. — The etiology of yellow fever. An additional note. [Read at Pan-Am. Med. 
Cong., Havana, Cuba, Feb. 4-7.] J. Am. Med. Ass., Chicago, v. 36 (7), Feb. 16, 
pp. 431-440, charts 1-6. 

1901b. --Experimental yellow fever. Am. Med., Phila,, v. 2 (1), July 6, pp. 15-23, 
charts 1-8, tables 1-2. 

REED, WALTER; CARROLL, JAMESJ AGRAMONTE, ARISTIDES; AND LAZEAR, JESSE W. 

1900. — The etiology of yellow fever. A preliminary note. [Read at Meeting of 
Am. Pub. Health Ass., Indianapolis, Ind., Oct. 22-26.] Phila. M. J. (148), v. 6 (17), 
Oct. 27, pp. 790-796, tables 1-3, charts 1-2. 

REED, WALTER, AND STERNBERG, GEORGE M. 

1895. — Report of immunity against vaccination conferred upon the monkey by the 
use of the serum of the vaccinated calf and monkey. Tr. Ass. Am. Physicians, Phila., 
v. 10, pp. 57-69. 



46 YELLOW FEVER. 

DR. REED'S WORK IN CUBA, BY MAJ. GEN. LEONARD WOOD, UNITED STATES ARMY. 

[Abstract.] 

The work of Dr. Walter Reed is the most important work in the 
way of medical research and discovery which has been accomplished 
by any one who has lived in this hemisphere. There is no other 
medical discovery to which it can be compared, unless it be thifcof 
anaesthesia. The results to humanity are incalculable and far-reach- 
ing. It is safe to say that this discovery has resulted in saving each 
year more lives than were lost in the war with Spain, and in a saving 
to commerce, and especially to the southern portion of our country, 
of an amount equal to the cost of the war with Spain. 

The following letters and telegrams were received: 

Washington, D. C, December 29, 1902. 
Dr. S. S. Adams, 

President District Medical Society. 

My Dear Dr. Adams: I regret exceedingly that an engagement made some time 
since, and from which I can not excuse myself, will prevent me from attending the 
Reed memorial meeting on Wednesday evening. 

No one appreciates more deeply than I do the loss to scientific medicine and to the 
medical corps of the army caused by Maj. Reed's death. His scientific work was 
eminently fruitful and far-reaching in its results. As the head of the medical corps 
during nine years of his most useful work, which was prosecuted under my general 
direction, I am of course entirely familiar with the results accomplished. 

Maj. Reed was endowed by nature and by training with the essential qualifications 
for engaging in research work in the special field to which he devoted his talents and 
his energies. Conservative, painstaking, thorough, persevering, and ready in resources, 
he acquitted himself with credit in every task assigned to him, and has achieved 
great and deserved distinction by his successful demonstration of the method by which 
yellow fever is transmitted from man to man. In addition to this, he was a modest 
and courteous gentleman, who attracted all of those who came in contact with him. 
His death came to me, as to his other numerous friends, as a great personal grief and 
irreparable loss. 

Very truly, yours, Geo. M. Sternberg. 



Baltimore, December 30, 1902. 
Dear Dr. Adams: I have to leave unexpectedly to-day for Canada. Please 
express my regrets that I can not be at the memorial meeting to Reed. 
With kind regards, sincerely yours, 

Wm. Osler. 



Richmond, Va., December 31, 1902. 
Maj. J. R. Kean, 

Surgeon GeneraVs Office, War Department, Washington, D. C: 
Greatly regret I can not attend the meeting to-night in honor of Dr. Reed, whose 
friendship I prized, whose character I admired, and whose contribution to science and 
country can not be measured. 

Fitzhugh Lee. 



Treasury Department, 
Public Health and Marine-Hospital Service, 

Washington, D. C, January 5, 1903. 
Dr. F. S. Nash, 

1723 Q Street, Washington, D. C. 
My Dear Dr. Nash: As you may know by this time, I have been absent from the 
city for a month and returned Saturday. On opening my mail to-day I find your 
note of December 9, and I wish to express my great regret that I could not have been 
here to accept the honor which was conferred upon me of responding at a meeting 
held in memory of Dr. Reed. It would have been a great privilege to have taken part 



YELLOW FEVEB. 47 

in that meeting, and of all the things which I have missed by being away one month 
I regret this more than any other. 

I had, during his life, the highest regard for Dr. Reed as a scientist, and, more than 
that, I had the warmest feeling of frienship toward him, although we were by no means 
intimate, and certinly his death was a blow to science and the whole governmental 
senuce. 

I had a conviction that in the near future the service of which I have charge would 
find a way of having some official connection with Dr. Reed in his great work, and that 
thrA|h him the bond of union between the medical services of the Government 
wouWbe materially strengthened. 

I have learned that Dr. Stiles took the place which was intended for myself, and 
I am much gratified that he did. 
"Very sincerely yours, 

Walter Wyaian. 



Chapter 6. 

VALUE OF DR. REED'S WORK AND EXPRESSION OF APPRE- 
CIATION. 1 

Popular appreciation of the value of the work of the Yellow Fever 
Commission has been singularly slow and imperfect. While nearly 
every educated person in the United States is familiar with the name 
and work of a distinguished Austrian surgeon who has recently 
demonstrated in this country an operation for the cure of a rather 
rare deformity in children, only a small fraction of them know any- 
thing of Walter Reed, the conqueror of the " yellow plague." And 
yet distinguished men have not been silent in regard to him. Gen. 
Leonard Wood said, in a recent address at a memorial meeting of 
scientific men held in honor of his memory in Washington: 

I know of no other man on this side of the world who has done so much for humanity 
as Dr. Reed. His discovery results in the saving of more lives annually than were 
lost in the Cuban war, and saves the commercial interests of the world a greater 
financial loss each year than the cost of the Cuban war. He came to Cuba at a time 
when one-third of the officers of my staff died of yellow fever, and we were dis- 
couraged at the failure of our efforts to control the disease. In the months when 
the disease was ordinarily worst the disease was checked and driven from Habana. 
That was the first time in nearly 200 years that the city had been rid of it. The 
value of his discovery can not be appreciated by persons who are not familiar with 
the conditions of tropical countries. Hereafter it will never be possible for yellow 
fever to gain such headway that quarantine will exist from the mouth of the Poto- 
mac to the mouth of the Rio Grande. Future generations will appreciate fully the 
value of Dr. Reed's services. His was the originating, directing, and controlling 
mind in this work, and the others were assistants only. 

In a letter dated November 24 General Wood said: 

To Maj. Reed belongs the honor of having led in the greatest medical work of modern 
times, and the results he accomplished will live for all time. 

Prof. William H. Welch, of Johns Hopkins, said in a letter to the 
Secretary of War : 

Dr. Reed's researches in yellow fever are by far the most important contributions 
to science which have ever come from an Army surgeon. In my judgment, they are 
the most valuable contributions to medicine and public hygiene which have ever 
been made in this country with the exception of the discovery of anaesthesia. They 
have led and will lead to the saving of untold thousands of lives. I am in a position 
to know that the credit for the original ideas embodied in this work belongs wholly 
to Maj. Reed. Such work, if done in Europe, would receive substantial recognition 
from the Government. 

He was last year given the degree of LL. D. by the University of 
Michigan, and the degree of M. A. by Harvard University. In con- 
ferring, the language used by President Eliot was: 

Walter Reed, graduate of medicine of the University of Virginia, the Army surgeon 
who planned and directed in Cuba the experiments which have given man control 
over that fearful scourge, yellow fever. 

i "The scientific work and discoveries of the late Maj.' Walter Reed, United States Army" (S. Doc. 
No. 118, Jan. 28, 1903) , ordered to be published. Prepared by Maj. Jefferson R. Kean. 

48 



YELLOW FEVER. ' 49 

Precedents are abundant for State aid to public benefactors and 
their families. The English Government a century ago, when the 
purchasing value of money was far greater than at present, gave to 
Jenner, the discoverer of vaccination, grants amounting to £30,000. 
He also received £7,383 from a subscription in India. 

Pasteur, the founder of the science of bacteriology, besides numer- 
ous honors and decorations and money donations from other sources, 
received from the French Government a pension of 12,000 francs. 

Lister, the originator of antiseptic surgery, has, besides numerous 
honors and decorations, been successively, knighted and elevated to 
the peerage. 

In this country a bill to donate $100,000 to the discoverer of anaes- 
thesia was twice passed by the Senate (in 1853 and 1854), but failed 
in the House, probably because of the uncertainty as to which of the 
rival claimants was entitled to the credit of that discovery. 

The resolutions of various scientific and professional societies are 
appended as an indication of the standing which Dr. Reed occupied in 
the scientific world at the time of his death. 

The following editorial from a prominent medical journal, American 
Medicine, is also quoted on account of its pertinence to the question: 

DUE REWARDS FOR SCIENTIFIC ACHIEVEMENTS. 

The recent death of Maj. Walter Reed directs attention to the self-sacrifice of the 
medical investigator and the inadequacy of the recognition which is attainable in 
America by these heroes of science. His demise deprives the country of a citizen 
whose public spirit, devotion to duty, and splendid achievements justly entitle him 
to an enduring testimonial. His scientific career, strictly speaking, began about 
1890, when, through the stimulating influence of his illustrious teacher, Dr. Welch, 
of Johns Hopkins, his interest was awakened in the intimate nature and underlying 
causes of disease, and he took up the special study of pathology and bacteriology. 
With rare native intelligence, indefatigable industry, high ideals, broad sympathies, 
and a personality that attracted all who came in contact with him, he soon distin- 
guished himself as a trustworthy, independent investigator, and entered upon a work 
that was to become a triumph for scientific medicine and a blessing to humanity. 
Notwithstanding his manifold duties as curator of the Army Medical Museum, Reed 
never lost his love for pure medical investigation, and was a frequent contributor to 
medical literature. Yet while his contributions in general to scientific medicine are 
uniformly as good as the best, they are insignificant when compared with the great 
work upon yellow fever with which his name will ever be inseparably associated. 
His was the master mind and he the guiding spirit in an investigation whereby mul- 
titudes of lives have been saved, a pestilential malady robbed of its mysteries and 
terrors, and an annual expenditure of millions of money shown to be in large part, 
if not entirely, needless. As has been said, his work "means to the United States for 
the future a saving in life and treasure that is cheaply paid for by the whole cost of 
the Spanish- American War." 

In other countries a man who had done such a work as Reed would at once receive 
office, honors, and financially security. In ours we leave him unrewarded, to work 
out his life, to die early, perhaps, and then we offer his family a sum as a pension 
small beyond ridicule. We appeal to Congress to demonstrate the nation's gratitude 
in this case. It should act promptly and in a manner commensurate with the mag- 
nificient public service rendered by our colleague. This, we are sure, is the wish of 
everyone conversant with what he has done. 

RESOLUTIONS OF MEDICAL SOCIETIES AND LEARNED BODIES WITH REF- 
ERENCE TO MAJ. WALTER REED, SURGEON, UNITED STATES ARMY. 

At a stated meeting of the New York Academy of Medicine, held 
December 3, 1902, the following resolution was unanimously adopted: 

Whereas in the recent death of Dr. Walter Reed, major and surgeon, United States 
Army, the science of medicine has lost the one whose brilliant research led first to the 

79965°— S. Doc. 822, 61-3 4 



50 YELLOW FEVER. 

demonstration of the transmission of yellow fever by the mosquito, and later to the 
practical removal of the disease from a large part of Cuba and the prevention of its 
transmission to the shores of this country: Be it 

Resolved, That the New York Academy of Medicine records its sense of the great- 
ness of the loss to science and to mankind and its sympathy with the friends and 
relatives of the deceased. 

The following minutes and resolutions were adopted at a special 
meeting of the faculty of the medical department of the Columbian 
University : 

The sudden and unexpected demise of our esteemed friend and colleague, Maj. 
Walter Reed, United States Army, professor of bacteriology and pathology in the 
medical school of the Columbian University, is an event that brings to us the most 
acute regret and overwhelming sorrow. 

Taken from us in the prime of manhood and in the zenith of his professional use- 
fulness, at a time when the medical profession and humanity at large were prepared 
to do him homage for his great work in demonstrating the method of exterminating 
yellow fever by protection from inoculating mosquitoes and by which that fatal 
disease has been abolished from some of its most malignant haunts — at a time, too, 
when his relations with the faculty and students of the Columbian University had 
become securely united by bonds of mutual affection and esteem — under these cir- 
cumstances it is with a most earnest and sincere feeling that we, the medical faculty 
of the Columbian University, hereby desire to express our unreserved admiration for 
the work, life, and character of Prof. Reed, both as a physician, a teacher, a trusted 
friend, and a man of science. In testimony whereof, it is hereby 

Resolved, That the foregoing note be recorded in the permanent archives of the 
faculty; that a copy of the same be given to the press for publication and also for- 
warded to the family of Dr. Reed as an evidence of our sympathy for them in their 
great sorrow. 

Resolved, That, as a further mark of respect for our lamented colleague, the exercises 
of the medical school be suspended and that the students and faculty attend in a 
body his funeral obsequies. 

The following resolutions were adopted by the medical faculty of 
the University of Virginia December 8, 1902, and by them reported to 
the general faculty, which heartily concurred in this expression of 
regard for the memory of Dr. Reed, of admiration for his work, and 
of sympathy for his family: 

The medical faculty of the University of Virginia have heard with deep sorrow 
of the death of Maj. Walter Reed, professor of bacteriology and pathology in the 
Army Medical School, and distinguished graduate of this medical department. 

His masterly investigation of the causes of the outbreaks of typhoid fever in the 
United States Army during the Spanish-American War, and especially his work 
furnishing conclusive proof of the conveyance of yellow fever by the mosquito, entitle 
him to a preeminent place amongst scientists and sanitarians and will prove of inesti- 
mable service to mankind. 

As an alumnus he was true and loyal, manifesting on every appropriate occasion 
his continued interest in the university, upon which he had reflected great credit. 

In testimony of our high appreciation of his character and achievements it is hereby 

Resolved, That the foregoing note be spread upon our minutes and a copy be for- 
warded to the family of Dr. Reed as an evidence of our sympathy for them in their 
great sorrow. 

RESOLUTIONS OF THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 

Resolved. That the American Association for the Advancement of Science hereby 
records its sense of the great loss sustained by science in the death of Maj. Walter 
R ed, surgeon in the United States Army, and its appreciation of the far-reaching 
and invaluable services which he has rendered to humanity. By solving the problem 
of the mode of spread of yellow fever, Maj. Reed not only made a great contribution 
to science, but at the same time conferred inestimable benefits upon his country and 
upon mankind. To have discovered and demonstrated the methods, which have 
already been successfully tested in Cuba, of eradicating a widespread and terrible 
pestilence, is a benefaction of imperishable renown, of incalculable value in the sav- 
ing of human lives, of vast importance to commercial interests, and deserving the 



YELLOW FEVER. 51 

highest rewards in the power of his countrymen to bestow. This association earn- 
estly urges upon the attention of Congress the duty of making full provision for the 
support of his family. 

Resolved, That the president designate a committee of nine members of this associa- 
tion, with. power to increase its number, which shall be authorized and requested to 
devise and carry out a plan or aid in similar efforts elsewhere instituted, by which 
a suitable and permanent memorial of this great benefactor of his race may be secured. 
This committee shall be authorized to prepare and publish a statement of the services 
of the late Maj. Reed in discovering the mode by which yellow fever may be exter- 
minated. 

The following resolution was adopted at the meeting of the Ameri- 
can Medical Association at Saratoga, N. Y., on June 11, 1902: 

Whereas the members of the American Medical Association believe that the recent 
work of the United States Army surgeons in Cuba in relation to the discovery of the 
method of transmission of yellow fever is of such magnitude and far-reaching benefi- 
cence as to rank only second with Jenner's discovery of vaccination; and 

Whereas the practical value of this discovery has been proven by the complete 
eradication of this scourge from Habana: 

Resolved, That the thanks of this association be tendered the gentlemen who 
accomplished this brilliant result, and particularly to Drs. Walter Reed, James Car- 
roll, A. Agramonte, W. O. Gorgas, and to Leonard Wood, who recognized the impor- 
tance of the work and made it possible by his hearty encouragement and assistance. 

Resolved, That this association, while deeply deploring the death of Dr. Jesse A. 
Lazear, who died a martyr to science, admires and gratefully acknowledges the heroic 
devotion of this physician and some of the members of the Hospital Corps to the cause 
of humanity. 

Resolved, That these resolutions be published in The Journal, and that copies be 
transmitted to Drs. Reed, Carroll, Agramonte, Wood, Gorgas, and Mrs. Lazear. 

RESOLUTIONS TAKEN BY THE INTERNATIONAL CONGRESS OF MEDICINE AT CAIRO, EGYPT, 

DECEMBER 22, 1902. 

Les membres du Premier Congres de Medecine en Egypte apprennant avec le plus 
profond regret la mort prematuree du Maj. Walter Reed du Corps Medical de l'Armee 
des Etats Unis d'Amerique. 

La part brillante et importante qu'il a pris dans la decouverte du moustique 
stegomyia comme le seul agent transmitteur du parasite de la fievre jaune, reussessant 
ainsi a mettre les ravages de cette terrible maladie sous le controle des hygienistes 
fait de sa mort une perte cruelle pour l'humanite. 

Le Congres decide en consequence d'exprimer a cette occasion toute sa sympathie 
au Corps Medical de l'Armee des Etats Unis ainsi qu'a la famille du Maj. Reed. 

Le Congres decide en outre de prier le secretaire du Congres d'envoyer ofncielle- 
ment par l'entremise des Autorites competentes une copie de la presente resolution 
au Chirurgien en Chef de l'Armee des Etat Unis d'Amerique et une autre egalment 
a Madame Veuve Reed. 

[From an editorial in American Medicine (referring to Maj. Reed).] 

His was the master mind and he the guiding spirit in an investigation whereby 
multitudes of lives have been saved, a pestilential malady robbed of its mysteries 
and terrors, and an annual expenditure of millions of money shown to be in large 
part, if not entirely, needless. 

[From the resolutions of the American Association for the Advancement of Science.] 

By solving the problem of the mode of spread of yellow fever Maj. Reed not only 
made a great contribution to science, but at the same time conferred inestimable 
benefits upon his country and upon mankind. To have discovered and demonstrated 
the methods, which have already been successfully tested in Cuba, of eradicating a 
widespread and terrible pestilence is a benefaction of imperishable renown, of incal- 
culable value in the saving of human lives, of vast importance to commercial interests, 
and deserving the highest rewards in the power of his countrymen to bestow. 

[From lecture of Sir Patrick Manson, M. D., medical adviser of the British Colonial Office.] 

Dr. Walter _ Reed did a great and beneficent work. We in England thoroughly 
appreciate this, and heartily sympathize with America in the loss she and the world 



52 YELLOW FBVEE. 

has sustained by his premature death . The best tribute we can pay to his memory is at 
once to anply his discovery. Let us hope that the good he has done will not be 
interred with his bones, and that his countrymen and the rest of us will take care to 
push forward the great and beneficent measures his brilliant labors so clearly indicate. 

Similar resolutions have been passed by numerous other scientific 
bodies. They are not given here because it is not desired unduly to 
lengthen this report. 

INCORPORATORS OF "THE WALTER REED MEMORIAL ASSOCIATION," WASHINGTON, D. C. 

R. M. O'Reilly, Surgeon General, United States Army, Washington, D. C. 

P. M. Rixey, Surgeon General, United States Navy, Washington, D. C. 

Walter Wyman, LL. D., Surgeon General, United States Public Health and Marine- 
Hospital Service, Washington, D. C. 

George M. Sternberg, LL. D., brigadier general, United States Army (retired), 
Washington, D. C. 

Calvin De Witt, brigadier general, United States Army (retired), Washington, D. C. 

Daniel C. Gilman, LL. D., president of Carnegie Institution, Washington, D. C. 

Chas. W. Needham, LL. D., president of Columbian University, Washington, D. C. 

Carroll D. Wright, LL. D., Commissioner of Labor, Washington, D. C. 

Henry B. F. Macfarland, president Board of Commissioners, District of Columbia. 

H. St. George Tucker, LL. D., dean of school of law and diplomacy, Columbian 
University, Washington, D. C. 

Alexander Graham Bell, LL. D., Columbian University, Washington, D. C. 

G. Wythe Cook, M. D., LL. D., Washington, D. C. 

A. F. A. King, M. D., dean emeritus medical school, Columbian University, Wash- 
ington, D. C. 

Chas. Wardell Styles, M. D., Chief of Division of Zoology, Hygienic Laboratory, 
United States Public Health and Marine-Hospital Service, Washington, D. C. 

W. J. Boardman, Washington, D. C. 

William A. Gordon, lawyer, Washington, D. C. 

Maj. J. R. Kean, surgeon, United States Army, War Department, Washington, D. C. 

Maj. W. D. McCaw, surgeon, United States Army, War Department, Washington, 
D. C. 

Capt. C. R. Darnall, assistant surgeon, United States Army, War Department, 
Washington, D. C. 

First Lieut. Jas. Carroll, assistant surgeon, United States Army, War Department, 
Washington, D. C. 

F. S. Nash, M. D., Washington, D. C. 



PART II —THE PUBLICATIONS OF WALTER REED AND HIS ASSOCIATES 
ON THE COMMISSION IN REGARD TO YELLOW FEVER, 



Chapter 1. 



BACILLUS ICTEROIDES AND BACILLUS CHOLERA SUIS— A 
PRELIMINARY NOTE. 

By Walter Reed, M. D., Surgeon, United States Army, and James Carroll, M. D., 
Acting Assistant Surgeon, United States Army. 

[Reprinted from the Medical News, April 29, 1899.] 

In the course of a comparative study of Bacillus x (Sternberg) and 
Bacillus icteroides (Sanarelli) which has engaged our attention as 
opportunity would permit during the past 18 months, we have had 
occasion to observe the effect produced by the intravenous injection 
in dogs of other micro-organisms, such as the Bacillus coli communis 
and the Bacillus cholerx suis. Without entering into details in this 
preliminary note we may state that the same clinical symptoms, 
viz, vomiting, increased action of the bowels, and profound prostra- 
tion, which are produced in dogs by the intravenous injection of B. 
icteroides, are also brought about by a like inoculation of the hog- 
cholera bacillus. When death occurs, the stomach contains a con- 
siderable quantity of fluid blood and extensive hemorrhagic lesions 
are present in the small intestine. We have not found fatty degenera- 
tion of the liver, since our dogs, few in number, injected with the hog- 
cholera bacillus, have died too early for this change to occur. We 
have also failed to discover any fatty degeneration in the liver of dogs 
that have died within a few days after the intravenous injection of 
B. icteroides. This change has only been met with in two instances, 
when the animals had survived until the ninth day after inoculation 
with B. icteroides. In neither of these cases, however, was the degree 
of fatty degeneration at all comparable with that present in the 
human liver in yellow fever. 

In addition to the experiments upon dogs, we have compared the 
course of the infection and the lesions produced in guinea pigs and 
rabbits inoculated with small quantities of B. icteroides and B. cholersc 
suis, and have been much impressed with the similarity of the results 
obtained. The same cyclical course of the infection described by 
Sanarelli for guinea pigs inoculated with B. icteroides is seen in these 
animals when injected with like quantities of B. cholerse suis. The 
greater susceptibility and shorter course of the infection in rabbits 
applies equally to both micro-organisms. Theobald Smith has called 
attention to the extreme susceptibility of these animals to inoculation 
with minute quantities of the hog-cholera bacillus. 1 We have suc- 

1 Bulletin No. 6, U. S. Department of Agriculture, 1894. 

53 



54 YELLOW FEVER. 

ceeded in killing rabbits with Tooib^p c.c. B. icteroides injected sub- 
cutaneously. The lesions produced in rabbits and guinea pigs inocu- 
lated with B. icteroides and the hog-cholera bacillus are practically 
the same, the most constant change consisting of multiple necroses in 
the liver. Sanarelli does not appear to have made any mention of 
this most striking lesion. We have found these punctate necroses of 
the liver especially prominent in guinea pigs that have survived the 
inoculation more than five days. 

Observations have shown that pigeons are not very susceptible to 
inoculation with the hog-cholera bacillus. We have also found these 
birds to be tolerably resistant to infection with B. icteroides. A fatal 
result has been produced by injecting 3 c.c. of bouillon culture into 
the breast muscle. Hemorrhage, swelling, and extensive necrosis of 
the muscle are present, under these circumstances, as has been 
described by Welch and Clement, for the hog-cholera bacillus. 1 

We desire also to record in this preliminary note that Bacillus 
icteroides, when fed to young hogs, produces an acute infection which 
may be followed by a fatal result, and that the chief lesion is confined 
to the large intestine. This lesion consists of an inflammation of the 
mucous membrane accompanied by fibrinous exudate, together with 
numerous small and large superficial ulcerations affecting the colon 
and cecum. These ulcerated areas are covered by an abundant, thick, 
bile-stained exudate. The "cork lining" appearance mentioned by 
Smith would apply to the description of the necrosed intestinal 
mucosa. A portion of the viscera of a young hog that had been fed 
with 25 c.c. of a 24-hour bouillon culture of Sanarelli's bacillus and 
which had died on the sixth day of the disease was fed to a second 
animal. The latter after exhibiting symptoms of sickness, such as 
fever, shiverings, and loss of appetite, for a few days appeared to have 
fully recovered from the inoculation. It was killed on the eighteenth 
day. At autopsy numerous ulcers in various stages of cicatrization 
were found in the large intestine. 

In another animal which died on the twelfth day after being 
fed 15 c.c. of a 24-hour bouillon culture of B. icteroides we found 
erosions upon the tongue, a well marked diphtheritic inflammation 
of the lining membrane of the esophagus from pharynx to stomach, 
involving the latter; eroded ulcers with hemorrhagic bases upon the 
gastric mucosa; superficial erosions and circumscribed ulcers, bearing 
a yellowish slough, in the small intestine and cecum; and, in addition, 
there were several hundred distinctly raised, neoplasmic, button-like 
elevations of about the size of a small split pea beneath the mucous 
membrane of the large bowel. A few of these showed a small, super- 
ficial, centrally situated spot of necrosis. The mucous membrane of 
the gall-bladder was the seat of a well marked necrotic inflammation, 
and there was also inflammation and erosion of the mucous membrane 
of the prepuce, which was distended with a dirty, yellowish-colored 
fluid. 

As regards the morphologic and biologic characters of B. icteroides 
and B. cholerse, suis we have been unable to observe differences other 
than may be met with in varieties of the same species. Both are 
small, quite actively motile, nonliquefying bacilli whose slow rate 
of growth is the same in bouillon and in gelatin ; likewise on agar, 

i "Hog Cholera and Swine Plague," Welch and Clement, 1894. 



YELLOW FEVER. 55 

potato, and in litmus milk the growth presents the same appear- 
ances. Milk is not coagulated by either of these bacilli. 

The action of B. icteroides and B. cholerse, suis upon the three sugars 
has been the same in our hands. Both ferment glucose. If the 
bouillon is free from muscle glucose no fermentation takes place in 
lactose or saccharose bouillon. Exceptionally we have recorded a 
very slight fermentation of saccharose with both organisms. Both 
of these bacilli, when cultivated in Dunham's solution, give a faint 
indol reaction. 

We desire further to record the marked agglutinative reaction 
exhibited toward the hog-cholera bacillus by the serum of an animal 
immunized with B. icteroides. As long ago as May, 1898, we had 
observed that the blood serum of a dog which was being immunized 
with B. icteroides would in dilutions of 1 to 5,000 promptly arrest 
motility and agglutinate the hog-cholera bacillus. After testing 
various dilutions of this serum from 1 to 100 to 1 to 5,000 we could 
observe no difference in its agglutinative reaction upon B. icteroides 
and B. cholerse suis. We have recently obtained, through the kind- 
ness of Surg. Gen. Sternberg, a specimen of Sanarelli's icteroides 
serum from Rio Janeiro, which, in dilutions of 1 to 120,000 promptly 
arrests the motility and agglutinates bacillus icteroides. In the 
same dilution this serum immediately arrests the motility of the hog- 
cholera bacillus, but does not bring about agglutination of the bacilli 
until at the end of about three hours. In a dilution of 1 to 30,000 
agglutination commences within ten minutes and is complete at the 
end of one hour. The groups of bacilli are smaller than occurs with 
B. icteroides. 

In rejecting B. icteroides as the specific cause of yellow fever Novy 
emphasizes the extreme resistance of this bacillus to low temperatures. 1 
We have found Sanarelli's bacillus to preserve its vitality and viru- 
lency after twenty days' continuous freezing at — 10° C. (14°F.). That 
the hogcholera bacillus is also quite resistant to low temperatures has 
been proven by the observations of Smith, and by the fact of its 
survival, notwithstanding the extreme severity of winter, in our 
Northwestern States. 

Putting together, therefore, the remarkable cultural resemblances 
of these two bacilli, and the similarity of their pathogenic action as 
shown in guinea-pigs, rabbits, pigeons, dogs, and hogs, we venture 
to express the opinion that bacillus icteroides (Sanarelli) is a variety 
of the hog-cholera bacillus, and that it should be considered only as 
a secondary invader in yellow fever. We find that bacillus x (Stern- 
berg) presents marked differences from the foregoing micro-organisms, 
both as regards its biologic characters as well as its pathogenic action 
toward animals. Reserving for future publication a more detailed 
description of our observations, it will suffice to here state our opinion 
that bacillus x should be placed with the colon group. 

» " The Etiology of Yellow Fever," Medical News, p. 368, Sept. 17, 1898. 



Chapter 2. 

THE ETIOLOGY OF YELLOW FEVER— A PRELIMINARY NOTE. 1 

By Walter Reed, M. D., Surgeon, United States Army, James Carroll, M. D.; 
A. Agramoxte, M. D., and Jesse W. Lazear, M. D., 2 Acting Assistant Surgeon, 
United States Army. 

The writers, constituting a board of medical officers convened "for 
the purpose of pursuing scientific investigations with reference to the 
acute infectious diseases prevalent on the Island of Cuba/' arrived 
at our station, Columbia Barracks, Quemados, Cuba, on June 25 of 
the present year, and proceeded, under written instructions from the 
Surgeon General of the Army, to "give special attention to questions 
relating to the etiology and prevention of yellow fever." 

Two of its members (Agramonte and Lazear) were stationed on the 
Island of Cuba, the former in Habana, and the latter at Columbia 
Barracks, and were already pursuing investigations relating to the 
etiology of this disease. 

Fortunately for the purposes of this board, an epidemic of yellow 
fever was prevailing in the adjacent town of Quemados, Cuba, at the 
time of our arrival, thus furnishing us an opportunity for clinical 
observations and for bacteriological and pathological work. The 
results already obtained, we believe, warrant the publication at this 
time of a preliminary note. A more detailed account of our observa- 
tions will be submitted to Surgeon General Sternberg in a future 
report. 

The first part of this preliminary note will deal with the results of 
blood cultures during fife and of cultures taken from yellow fever 
cadavers, reserving for the second part a consideration of the 
mosquito as instrumental in the propagation of yellow fever, with 
observations based on the biting of nonimmune human beings by 
mosquitoes which had fed on patients sick with yellow fever, at 
various intervals prior to the biting. 

In prosecuting the first part of our work, we isolated a variety of 
bacteria, but of these we do not propose to speak at present. It will 
suffice for our purpose if we state the results as regards the finding of 
bacillus icteroides, leaving the mention of other bacteria to our detailed 
report. 

The cases studied during the Quemados epidemic had been diag- 
nosed by a board of physicians selected largely by reason of their 
familiarity with yellow fever. This board consisted of Drs. Mcola 
Silverio, Manuel "Herera, Eduardo Angles, and Acting Asst. Surgs. 
Roger P. Ames and Jesse W. Lazear, United States Army. 

Those studied in Habana were patients in Las Animas Hospital 
and had been diagnosed as such by a board of distinguished practi- 
tioners of that city. 

An examination of Table I will show the character of the attacks. 

The milder cases studied, few in number, were attended by jaundice 
and albumen in the urine. 

1 Reprinted from the Proceedings of the Twentv-eighth Annual Meeting of the American Public Health 
Association, Indianapolis, Ind., Oct. 22, 23, 24, 25, and 26. 1900. 

2 Died of yellow fever at Columbia Barracks, Cuba, Sept. 25, 1900. 

56 



YELLOW FEVER. 



57 



I. Bacillus Icteroides (Sanarelli) as the Cause of Yellow 

Fever. 

The claim of Sanarelli for the specific character of B. icteroides as 
the causative agent in yellow fever has excited such wide attention 
since the publication of his observations that it seemed to us of the 
first importance to give our undivided attention to the isolation of 
this microorganism from the blood of those sick with yellow fever 
and from the blood and organs of yellow-fever cadavers. 

(a) cultures taken from the blood during life. 

The method followed was that ordinarily used in an attempt to 
isolate bacteria from the circulating blood, viz, from a vein at the 
bend of the elbow a sufficient quantity of blood was taken with a 
hypodermic syringe, made sterile hj boiling, and after careful cleans- 
ing of the skin with soap and water, followed by equal parts of abso- 
lute alcohol and ether, and 1-2000 bichloride solution. 

Exceptionally, the blood withdrawn was plated on agar, but as a 
rule it was immediately transferred to sterile bouillon tubes (10 c. c.) 
in quantities of 0.5 c. c. to each of several tubes. These were then 
incubated at 35° to 37° C. for a period of one week. They were 
examined daily, and if growth was observed plates in agar or gelatine, 
or both, were made and the colonies carefully studied by transference 
to ordinary laboratory media. 

Eighteen cases have thus been carefully studied; of these 11 
were designated as " severe" cases of yellow fever, with 4 deaths; 3 as 
"well-marked" cases, with no deaths; and 4 as "mild" cases, with 
no deaths. 

From these 18 cases blood cultures were made, as shown in the 
following table : 

Table I. — Blood cultures during life. 



Day of disease. 


Character of attack. 


Number 
of cul- 
tures. 


Number 
of bouil- 
lon tubes 
inocu- 
lated. 


B. icteroides. 


First 




3 
1 
1 
6 
1 
1 

2 
5 
2 

1 
5 
1 
1 
4 
1 
1 
1 
2 
1 
1 


i 4 
4 
3 

18 
2 

23 

2 18 

4 

14 

6 

1 

112 
3 
1 
6 
2 
2 
2 
6 
2 
2 


Negative. 


Do 




Do. 


Do . 


Mild. 


Do. 






Do. 


Do... 




Do. 


Do 


Mild 


Do. 


Third 


Severe 


Do. 


Do 


Mild 


Do. 


Fourth 




Do. 


Do .. 




Do. 


Do... 


Mild 


Do. 


Fifth .. 




Do. 


Do... 




Do. 


Do 


Mild 


Do. 


Sixth 




Do. 


Do 




Do. 






Do. 


Do... 




Do. 


Eighth 

Do 




Do. 




Do. 


Ninth 




Do. 









agar plates. 



agar plates. 



Number of cultures 

Number of bouillon tubes inoculated. 
Number of agar plates 



48 
115 
15 



58 



YELLOW FEVEE. 



It will be seen that of 48 separate cultures made from the blood on 
various days of the disease and representing 115 bouillon inoculations 
and 18 agar plates, we failed to find Bacillus icteroides in any of our 
tubes or plates. 

The results of cultures taken in 18 1 cases of unmistakable yellow 
fever, on various days of the disease and in some cases on every day 
from the onset to death or recovery, would seem to exclude the 
presence of Bacillus icteroides in the blood of these cases during life. 

It will therefore be seen that while Wasdin and Geddings taking 
cultures from the ear lobe (Report on the Cause of Yellow Fever, 
1899), record that "in the blood of yellow-fever cases extracted 
during life Bacillus icteroides has been found in 13 of the 14 cases, 
with 1 negative " (92.85 per cent), we, by withdrawing blood from 
the veins of 18 patients, have to record 100 per cent of failures. 

We have already stated that we will reserve for a later report a 
description of the bacteria isolated from the blood in these cases. We 
now remark that but tew organisms were obtained and that, as a 
rule, our blood cultures gave no growth whatever. 

(b) cultures from yellow-fever cadavers. 

We tried to obtain autopsies very soon after death and sometimes 
succeed in doing so. Tubes containing about 10 c. c. of flesh-peptone 
bouillon were generally used for the first inoculation, direct from the 
blood and organs. As soon as the laboratory was reached, agar plates 
were made from these inoculated bouillon tubes, the former as well 
as the latter being then incubated at 35°-37° C. In nearly every 
case gelatin plates were also made from the recently inoculated 
bouillon tubes and kept at a temperature of 19°-20° C. 

If colonies were found in the agar or gelatin plates on the following 
days, the corresponding bouillon tubes were also plated on agar and 
gelatin. The bacteria thus found in our plates were carefully iso- 
lated and studied upon the usual nutritive media, so as to enable us 
to identify them if possible. We will here content ourselves with 
giving the results as regards the presence of B. icteroides only. 

Table II. 



No. of 

case. 


Day of disease. 


Time of autopsy. 


Source of culture. 


B. icteroides. 


1 


Seventh 

Sixth 


2 hours after death 




Negative. 
Do. 


2 


do 


3 


Fourth 

Eighth 

Fourth 


8 hours after death 


do... 


Do. 


4 
5 


4 hours after death 

do 


Abdominal cavity, blood, liver, spleen, 
kidney, bile, duodenum. 

Blood, liver, spleen, kidney, bile, duode- 
num. 

Abdominal cavity, blood, pericardial 
fluid, lung, spleen, kidney, liver, bile, 
duodenum. 

Blood, lung, liver, spleen, kidney, bile, 
jejunum. 

Blood, lung, liver, spleen, kidney, urine, 
small intestine. 


Do. 
Do. 


6 


Sixth. 


6 1 hours after death . . . 

50 minutes after death . 

\ hour after death 

2 hours after death 

7 hours after death 

\ hour after death 


Do. 


7 
8 
9 


do 

do 

Fourth 

Fifth 


Do. 
Do. 
Do. 


10 


Liver, kidney, spleen, small intestine 


Do. 


11 


Third 


Do. 











1 Cultures from the blood during life had been taken by Dr. Lazear in three other cases of yellow fever, 
but owing to the death of our colleague, the necessary data as to the day of the disease on which cultures 
had been "taken can not be ascertained. These cultures were negative as regards the finding of Sanarelli's 
bacillus. 



YELLOW FEVER. 59 

Our failure to isolate B. icteroides in these 11 autopsies of yellow- 
fever patients was a result winch we had not anticipated. One of us 
(Agramonte) who at Santiago, Cuba, during the epidemic of 1898, 
succeeded in finding B. icteroides in 33 per cent of his autopsies, has 
been much surprised at the absence of this bacillus in cultures from 
cadavers sectioned in Habana during the present year. In 2 of the 
1 1 cases we had reason to believe that from the character of colonies 
seen in gelatin plates we would be able to isolate B. icteroides. These 
colonies, however, when transferred to other media and carefully 
studied, did not prove to be this bacillus. We wonder whether other 
observers have occasionally relied upon the appearance of colonies in 
gelatin plates without further study. We only mention this as a pos- 
sible explanation of the large percentage of positive results recorded 
by some observers. 

Pothier, of New Orleans, La., only succeeded, however, in isolating 
B. icteroides in 3 out of 51 autopsies. (Journal of American Medical 
Association, Apr. 16, 1898.) 

Lutz (Revista DTgiene e Sanita Publica, XI, No. 13, July, 1900, 
pp. 474-475), says, as the result of his extensive observations on yellow 
fever, that Bacillus icteroides can not be found by present laboratory 
methods in more than half of the cases of yellow fever, and that when 
present the colonies are few in number. 

It is possible that our future autopsies may give more favorable 
results as regards B. icteroides. 

II. The Mosquito as the Host of the Parasite of Yellow Fever. 

Having failed to isolate B. icteroides either from the blood during 
life or from the blood and organs of cadavers, two courses of procedure 
in our further investigations appeared to be deserving of attention, viz, 
first, a careful study of the intestinal flora in yellow fever in compari- 
son with the bacteria that we might isolate from the intestinal canal of 
healthy individuals in this vicinity or of those sick with other dis- 
eases; or, secondly, to give our attention to the theory of the propaga- 
tion of yellow fever by means of the mosquito — a theory first advanced 
and ingeniously discussed by Dr. Carlos J. Finlay, of Habana, in 1881. 
(Anales de la Real Academia, vol. 18, 1881, pp. 147-169.) 

We were influenced to take up the second line of investigation by 
reason of the well-known facts connected with the epidemiology of 
this disease, and of course by the brilliant work of Ross and the Italian 
observers in connection with the theory of the propagation of malaria 
by the mosquito. 

We were also much impressed by the valuable observations made 
at Orwood and Taylor, Miss., during the year 1898, by Surg. Henry 
R. Carter, United States Marine-Hospital Service.. A note on the 
interval between infecting and secondary cases of yellow fever, etc. 
(Reprint from New Orleans Medical Journal, May, 1900.) We do not 
believe that sufficient importance has been accorded these painstaking 
and valuable data. We observe that the members of the yellow-fever 
commission of the Liverpool School of Tropical Medicine, Drs. Dur- 
ham and Myers, to whom we had the pleasure of submitting Carter's 
observations, have been equally impressed by their importance. 
(British Medical Journal, Sept. 8, 1900, pp. 656-657.) 



60 YELLOW FEVER. 

The circumstances under which Carter worked were favorable for 
recording with considerable accuracy the interval between the time of 
arrival of infecting cases in isolated farmhouses and the occurrence of 
secondary cases in these houses. According to Carter, "the period 
from the first (infecting) case to the first group of cases infected at 
these houses is generally from two to three weeks." 

The houses having now become infected, susceptible individuals 
thereafter visiting the houses for a few hours fall sick with the disease 
in the usual period of incubation — one to seven days. 

Other observations made by us since our arrival confirmed Carter's 
conclusions, thus pointing, as it seemed to us, to the presence of an 
intermediate host, such as the mosquito, which, having taken the 
parasite into its stomach soon after the entrance of the patient into 
the noninfected house, was able after a certain interval to reconvey 
the infecting agent to other individuals, thereby converting a non- 
infected house into an "infected" house. This interval would appear 
to be from 9 to 16 days (allowing for the period of incubation), which 
agrees fairly closely with the time required for the passage of the 
malarial parasite from the stomach of the mosquito to its salivary 
glands. 

In view of the foregoing observations we concluded to test the 
theory of Finlay on human beings. According to this author's obser- 
vation of numerous inoculations in 90 individuals, the application of 
one or two contaminated mosquitoes is not dangerous, but followed 
in about 18 per cent by an attack of what he considers to be very 
benign yellow fever at the most. 

We here desire to express our sincere thanks to Dr. Finlay, who 
accorded us a most courteous interview, and has gladly placed at our 
disposal his several publications relating to yellow fever during the 
past 19 years; and also for ova of the species of mosquito with 
which he had made his several inoculations. An important observa- 
tion to be here recorded is that, according to Finlay's statement, 30 
days prior to our visit, these ova had been deposited by a female just 
at the edge of the water in a small basin, whose contents had been 
allowed to slightly evaporate, so that these ova were at the time of our 
visit entirely above contact with the water. Notwithstanding this 
long interval after deposition, they were promptly converted into the 
larval stage, after a short period, by raising the level of the water in 
the basin. 

With the mosquitoes thus obtained we have been able to conduct 
our experiments. Specimens of this mosquito forwarded to Mr. L. 
O. Howard, entomologist, Department of Agriculture, Washington, 
D. C, were kindly identified as Culexfasciatus Fabr. 

In this preliminary note we have not space to refer at length to 
the various interesting and valuable contributions made by Finlay to 
the mosquito theory for the propagation of yellow fever. In addition 
to the paper already quoted, his most valuable contributions to this 
important theory are to be found in the articles designated as follows: 
Estadistica de las Inoculaciones con mosquitos contaminados, etc., 
reprint, Havana, 1891; Fiebre Amarilla, Estudio Clinico Patologicoy 
Etiologico, reprint, Habana, 1895; and Yellow Fever Immunity — 
Modes of Propagation: Mosquito Theory, 8th Congress of Interna- 
tional Hygienic and Demography, Budapest, 1894. 



YELLOW FEVER. 61 

His present views on this subject may be stated in his own language : 
11 First, reproduction of the disease, in a mild form, within 5 to 
25 days after having applied contaminated mosquitoes to susceptible 
subjects. Second, partial or complete immunity against yellow fever 
obtained when even no pathogenous manifestation had followed 
those inoculations. " (Medical Record, vol 55, No. 21, May 27, 1899.) 

Without reviewing the cases regarded as mild forms by the author 
of this theory, we believe that he has not as yet succeeded in repro- 
ducing a well-marked attack of yellow fever within the usual period 
of incubation of the disease, attended by albumen and jaundice, and 
in which all other sources of infection could be excluded. 

The experiments made by us on eleven nonimmune individuals are 
embraced in the following table, which should be carefully studied. 

The mosquito used in all cases was Culexfasciatus Fabr. 



62 



YELLOW FETEB. 

O - 5 



ooxcecRetc^nno^o .-■ cxoc :■". w ~ x. 



c * = :-? 



I - 



-: - r. - .- 




2 > £ >i 



I 5 



^;"v:"^;^:i:ii sc ti si 



soocoooa c 



r - ' — - ~ '-' 



-=. re ."- X ~ 



Zi 



YELLOW FEVER. 63 

It will be seen that we record 9 negative and 2 positive results. 
It is. we think, important to observe that of the 9 failures to infect. 
the time elapsing between the biting of the mosquito and the inocu- 
lation of the healthy subject varied in 7 cases from 2 to S daws (Nos. 1 . 
2. 3. 4. 5. 7. and 9 . and in the remaining two from 10 to 13 davs (Nos. 
6 and' 8). [ 

Five individuals out of the 9 who failed to show any result (Xos. 
2, 3, 4. 5, and 6j were inoculated by mosquitoes that had bitten very 
mild cases of yellow fever on the fifth day of the disease, and one 
individual by a mosquito that had bitten a mild case of yellow fever 
on the seventh day of the disease. (This latter patient was discharged 
from hospital 3 days later.) To this fact may possibly be attributed 
the negative results. Of the remaining 3 negative cases (Nos. 7. s. 
and 9). and which had been inoculated by mosquitoes that had bitten 
severe cases of the disease, the interval between the bite and the 
inoculation varied from 2 to 6 days. 

In the 2 cases (Xos. 6 and 5; where the interval was respectively 
10 and 13 days, the inoculations had been made with mosquitoes that 
had bitten very mild cases of yellow fever on the fifth day of the 
attack. Xo. S was also bitten by a mosquito which had been infected 
by a severe case of yellow fever 3 days before. 

TVe refrain from commenting further at this time upon the 9 
negative cases, preferring to record the results obtained rather than 
to indulge in speculation. 

Of the two cases which we have recorded as positive in Table III. 
we now propose to speak at greater length. 

Case 10. — Dr. James Carroll, acting assistant surgeon. United States Army, a member 
of this board, was bitten at 2 p. m.. August 27. 1900. by Culexfasciatus. This particu- 
lar mosquito had bitten a severe case of yellow . - _/_ iayofthe lisea: 
days before: a mild case of yellow fever, on the first day of the attacl ^ding; 
a severe case of yellow fever, on the second day of the attack, 4 days before; a mild 
case of yellow fever, on the second day of attack. 2 days before inoculation. 

Dr. Carroll remained well until the afternoon of the 29th. when he states that he 
felt tired, and for this reason, when on a visit to Laa Animas Hospital, the same after- 
noon (29th . some time between 4 and 6 p. m.. after visiting a few patients, he left 
the wards and waited outside on the porch, while his companions remained in the 
wards. 

August SO: During the afternoon, although not feeling well. Dr. Carroll visited La 
Playa. distant about H miles from Columbia Barracks, and took a - 

August Si. a. m.: Dr. Garroll realized that he was sick and that he had i ogh 

he retrained from taking his temperature, but did visit the labors - 

140 yards, for the purpose of examining his blood for the malarial 
examination was negative. During the afternoon he was compelled to take to his 
bed. At 7 p. m. temperature was 102° F. No headache nor backache: only a - 
of great lassitude. Eyes injected and face suffused. 

September 1. 7 a. m.: Temperature 102 c F. Blood again carefully examined by Dr. 
Lazear with negative results. 

11 a. m.: Temperature 102 = . 

The case having been diagnosed ever, Dr. Carroll was at noon 

removed to the yellow fever wards. 

9 p. m.: Temperature 102.8°, pulse 90: 12 o'clock rnidnieht. temperature 103.4°, 
pulse 84. 

September 2. S a. m.: Temperature 103. 6 C . pulse SO. A trace of albumen was r_:~ 
found in the urine. The subsequent history of the case was one of severe yellow 
fever. Jaundice appeared on September 3. 

The accompanying chart Xo. 1 contains all of the necessary data. 

The question of diagnosis having been clearly and easily estab- 
lished, it now becomes important to follow Dr. Carroll's movements 
for a period of 10 days preceding the mosquito inoculation, and 



64 



YELLOW FEVER. 



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YELLOW FEVEE. 65 

during the period elapsing from the bite of the insect until the com- 
mencement of the attack. 

On August 21, 22, and 23, Dr. Carroll was at Columbia Barracks, 
outside of the epidemic zone. On August 24 he visited the autopsy 
room of Military Hospital No. 1, which is situated on Principe Hill 
overlooking the city of Habana. He was present in this autopsy 
room while an autopsy was made by Dr. Agramonte on a case of per- 
nicious malarial fever. Dr. Carroll only took cultures from the 
blood and organs as the section proceeded. He was there about half 
an hour and then returned to Columbia Barracks. Subsequent 
microscopic study of sections of the liver and spleen showed that the 
case autopsied on the 29th was really a case of pernicious malarial 
fever. 

It should be stated that although cases of yellow fever are not 
admitted to Military Hospital No. 1, an English sea captain had been 
admitted to its wards a few days before, whose case developed into 
one of yellow fever with fatal result, and the body had been autopsied 
by Dr. Agramonte in this dead room on the day preceding Dr. Car- 
roll's visit to it. 

According to Dr. Carroll, the room was by no means in a cleanly 
condition. As Dr. Carroll's visit to this room was made on August 24, 
and as he began to complain on August 29, about the average period 
of incubation of yellow fever, there is a possible chance for infection 
in this way. We must call attention, however, to the fact that Dr. 
Agramonte, whenever he performs an autopsy in this room, is always 
attended by a young soldier of the Hospital Corps, United States 
Army, who is detailed for that purpose, and whose duty it is to assist 
and to afterwards attend to the cleaning of the autopsy table. This 
soldier, a nonimmune American, was present when Dr. Carroll was 
there and remained afterwards to attend to his duties. He has not 
contracted yellow-fever by his duties in this room from time to time. 
Our own experience would seem to accord with that of others, viz, 
that attendance upon autopsies and the handling of portions of 
organs of yellow-fever cases removed to the laboratory is unattended 
with danger. Certainly the three nonimmune members of this board, 
up to the time of these mosquito inoculations, had during the past 
three months come in close contact with the dead bodies and organs 
of yellow-fever cases, freely handling and examining these organs, 
including the small intestine, even kept at thermostat temperature 
for 24 hours, without contracting the disease. We have, of course, 
never neglected to cleanse our hands with disinfectants. 

Dr. Carroll upon his visit to the before-mentioned dead room only 
used the platinum loop for taking cultures and did not come in contact 
with the autopsy table. * 

The only other opportunity for infection in his case would appear 
to have been during his visit to Las Animas Hospital, situated in the 
suburbs of Habana, as here yellow-fever patients are admitted in 
large numbers. We have already pointed out that Dr. Carroll was 
complaining of lassitude at the hour of his visit, which was about 50 
hours after his inoculation with the contaminated mosquito. We 
have also called attention to the fact that he remained for the greater 
part of his visit outside of the hospital, on the piazza. This would 
79965°— S. Doc. 822, 61-3 5 



66 YELLOW FEVEE. 

appear to cast doubt upon his visit to Las Animas as the source of 
his infection. 

We do not wish to be understood as unnecessarily seeking to lay 
too much emphasis upon the exclusion in tins case of other" sources 
of infection than the mosquito, as we fully appreciate that Dr. Carroll 
had been on two occasions within the epidemic zone during the week 
preceding his attack of yellow fever. His movements on these occa- 
sions we have already given. 

We will again refer to Dr. Carroll's case after we have given the 
history of case Xo. 11, which we have designated as our second posi- 
tive result. 

Gase 11. — X. Y.. white. American, a resident of the military reservation of Colum- 
bia Barracks, was bitten during the forenoon of the 31st day of August, 1900, by the 
same mosquito that had bitten case 10 ^Dr. Carroll) 4 days before, and which hi the 
meanwhile had bitten a mild case of yellow fever (^ first day 1 2 days before being applied 
to X. Y. 

X. Y. was also bitten by a second mosquito that had been applied to a fatal case 
of yellow fever ^second day) 12 days before, and to 2 mild cases (second day) 4 and 10 
days previously: also, by a third mosquito that had bitten a fatal case of yellow fever 
^second day) 12 days before, a severe case i^first day' 2 days before, and 3 mild cases 
(first, second, and third day") 4. 6. and 10 days before: finally, by a fourth mosquito 
that had bitten 3 severe cases of yellow fever (all on the first day) 2, 4, and S days 
previously, and 1 mild case ^ecoud day) 6 days before. ^Yide Table III.) 

It will thus be seen that X. Y. was bitten by 4 mosquitoes, 2 of which had bitten 
severe (fatal) cases of yellow fever 12 days previously, one of which had bitten a severe 
case vsecond day) 16 days before, and one which had bitten a severe case (first day) 
S days before. 

September 25. — X. Y. began to experience a sense of dizziness and disinclination to 
work. This was just 5 days from the time of the mosquito inoculation. 

Twenty-four hours later, still dizzy and light-headed in attempting to move about. 
During the afternoon (sixth day after inoculation) chilly sensations, followed by fever 
and restlessness during the night. 

On the following day (seventh day after inoculation \ S a. in., temperature 102. S° F., 
eyes slightly injected, face suffused. Patient removed to the yellow fever wards; 
9 a. m.T temperature 103° F., pulse 66. A trace of albumen was found in the urine 
during the afternoon (third day of the attack"). This increased during the following 
days. Conjunctivae slightly jaundiced on the fourth day of disease, which was more 
distinct and could be plainly seen on anterior aspect of chest on the fifth and following 
day. Bleeding from the gums was noticed on the third and subsequent days after 
admission. Repeated examinations of the blood failed to show any malarial parasites. 

The course of the fever, the appearance of albumen in the urine, 
with jaundice and hemorrhage from the gums, together with the slow 
pulse, all pointed distinctly to the diagnosis of yellow fever. His 
attending physician, Dr. Roger P. Ames. United States Army, an 
expert in the diagnosis and treatment of this disease, did not hesitate 
to diagnose X. Y.'s attack as one of " well-pronounced yellow fever." 
Dr. Ames was not cognizant of the method of inoculation in this case. 
(Mde, Chart II.) 

The diagnosis, therefore, not being in doubt, we must follow this 
patient's movements during the 10 days preceding the bite of the 
mosquitoes and from this time until 5 days later, when the attack 
began. It so happens that we can follow X. Y.'s movements for a 
much longer period. Fifty-seven days prior to his inoculation, he 
spent a day and night in the city of Habana. Sixteen days before the 
inoculation, he rode on horseback with 6 other nonimmunes a dis- 
tance of about \\ miles toward the seashore and returned to his 
dwelling, without in the meantime dismounting from his horse. 
From this time until his complete convalescence was established, he 



YELLOW FEVER. 



67 



had remained within the immediate vicinity of his home. So that it 
may be positively stated that X. Y. had not absented himself from the 
military reservation of Columbia Barracks during a period of 57 
days prior to his inoculation (with the exception above stated), 
nor between the date of his inoculation and the establishment of con- 
valescence. 

Let us now inquire whether the military reservation of Columbia 
Barracks is outside of the epidemic zone of yellow fever. To this 



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we answer that since the commencement of the present epidemic of 
yellow fever in Habana, dating from May, 1900, the average monthly 
population of this station, including civilian employees, has been 
1,400, nearly all of whom are young nonimmunes. 

There have occurred amongst this nonimmune population from 
May 1 to October 13, 1900, 16 cases of yellow fever, all of which 
have been easily and readily traced to a visit to within the boundaries 
of the epidemic zone, except cases 10 and 11 of Table III, and 1 



68 YELLOW FEVEE. 

other case of which we shall presently speak. These cases have been 
distributed as follows: 

Cases. 

May 24 1 

June 10 1 

June 17 1 

June 19 2 

June 21 1 

June 29 1 

July 9 1 

July 26 1 

July 29 1 

Aug. 11 1 

Aug. 12 1 

Aug. 16 1 

Aug. 31 1 

Sept. 7 1 

Sept. 19 1 

Total 16 

Ten of these cases have occurred amongst an average monthly 
military population of 1,295 men, and 6 cases in an average civilian 
population of 105. 

Whenever these cases have occurred, as soon as the patient has 
been removed to hospital most careful measures of disinfection have 
been immediately carried out by a trained sanitary squad, under the 
personal supervision of a medical officer. These have consisted of 
destruction by fire of mattresses, the disinfection of bedding and 
clothing with 1 to 500 bichloride solution, and the application of the 
same solution freely to the ceiling, walls, and floors by means of a 
force pump. 

We repeat that no case has ever been connected with a preceding 
case, but that the source of infection has been readily shown to have 
occurred during the individual's visit to Habana, 6 miles distant, or 
to some other nearer Cuban settlement. 

We now invite attention to the fact that from August 17 to October 
13, a period of 57 days, only 3 cases of yellow fever have occurred 
amongst this population of 1,400 nonimmune Americans, and we 
consider it very important to note that two of these had been bitten, 
within 5 days of the commencement of their attack, by contaminated 
mosquitoes. 

Taken in connection with case 2, in which we have been unable to 
find any other source of infection than the bite of an infected mos- 
quito, 5 days preceding the attack, the case of Dr. Carroll (case 
10, Table III) becomes strongly confirmatory of the same origin. 

We will now briefly give the history of the third case of yellow fever 
that has occurred at Columbia Barracks during the period August 17 
to October 13, 1900. 

In the light of cases 10 and 11 we consider this case of sufficient 
importance to be here included, especially as it is one that might be 
possibly designated as a case of accidental infection by a mosquito. 

Case.— Dr. Jesse W. Lazear, acting assistant surgeon, United States Army, a member 
of this board, was bitten on August 16, 1900 (case 6, Table III), by a mosquito (Culex 
fasciatus) which 10 days previously had been contaminated by biting a very mild 
case of yellow fever (fifth day). No appreciable disturbance of health followed this 
inoculation. 

September 13, 1900 (forenoon): Dr. Lazear, while on a visit to Las Animas Hospital, 
and while collecting blood from yellow-fever patients for study, was bitten by a Culex 



Vl.LLOW FEVER. . 69 

mosquito (species undertermined). As Dr. Lazear had been previously bitten by a 
contaminated insect without after effects, he deliberately allowed this particular 
mosquito, which had settled on the back of his hand, to remain until it had satisfied 
its hunger. 

On the evening of September 18, 5 days after the bite, Dr. Lazear complained of 
feeling "out of sorts," and had a chill at 8 p. m. 

September 19: Twelve o'clock noon, temperature 102.4°, pulse, 112. Eyes injected, 
face suffused; 3 p. m., temperature, 103.4°, pulse, 104; 6 p. m., temperature, 103.8°, 
pulse, 106. Albumen appeared in the urine. Jaundice appeared on the third day. 
The subsequent history of this case was one of progressive and fatal yellow fever, the 
death of our much lamented colleague having occurred on the evening of Septem- 
ber 25, 1900. 

As Dr. Lazear was bitten by a mosquito while present in the wards 
of a yellow-fever hospital, one must, at least, admit the possibility of 
this insect's contamination by a previous bite of a } r ellow-fever 
patient. This case of accidental infection therefore can not fail to 
be of interest, taken in connection with cases 10 and 11. 

For ourselves, we have been profoundly impressed with the mode of 
infection and with the results that followed the bite of the mosquito 
in these three cases. Our results would appear to throw new light 
on Carter's observations in Mississippi, as to the period required 
between the introduction of the first (infecting) case and the occur- 
rence of secondary cases of yellow fever. 

Since we here, for the first time, record a case in which a typical 
attack of yellow fever has followed the bite of an infected mosquito, 
within the usual period of incubation of the disease, and in which 
other sources of infection can be excluded, we feel confident that the 
publication of these observations must excite renewed interest in the 
mosquito theory of the propagation of yellow fever, as first proposed 
by Finlay. 

From our study thus far of yellow fever, we draw the following 
conclusions : 

1. Bacillus icteroides (Sanarelli) stands in no causative relation to 
yellow fever, but when present should be considered as a secondary 
invader in this disease. 

2. The mosquito serves as the intermediate host for the parasite of 
yellow fever. 



Chapter 3. 

THE ETIOLOGY OF YELLOW FEVER.— AN ADDITIONAL NOTE. 1 

Walter Reed, M. D., Surgeon, United States Army, Jas. Carroll, M. D., and Aris- 
tides Agramonte, M. D., Acting Assistant Surgeons, United States Army. 

At the twenty-eighth annual meeting of the American Public Health 
Association, 2 held in Indianapolis, Ind., October 22-26, 1900, we pre- 
sented, in the form of a preliminary note, the results of our bac- 
terio logic study of yellow fever, based on cultures taken from the blood 
in 18 cases at various stages of the disease, as well as on those which 
we have made from the blood and organs of 11 yellow-fever cadavers. 
We also recorded the results obtained from the inoculation of 11 non- 
immune individuals by means of the bite of mosquitoes (Gulex fascia- 
tuSj Fabr.) that had previously fed on the blood of patients sick with 
yellow fever. We were able to report two positive results, in which 
the attack of yellow fever followed the bite of a mosquito within the 
usual period of incubation of this disease. 

In one of these cases all other sources of infection could be posi- 
tively excluded. From our several observations we drew the follow- 
ing conclusions: (1) Bacillus icteroides (Sanarelli) stands in no causa- 
tive relation to yellow fever, but when present should be considered 
as a secondary invader in this disease. (2) The mosquito serves as 
the intermediate host for the parasite of yellow fever. Since the pub- 
lication of our preliminary note we have continued our investigations, 
especially as regards the means by which yellow fever is propagated 
from individual to individual, and as to the manner in which houses 
become infected with the contagium of this disease. The results 
already obtained are so positive and striking that, with the permis- 
sion of Surg. Gen. Sternberg, we have concluded to present to this 
congress an additional note, in which we will record these later 
observations. We desire to here express our sincere thanks to the 
military governor of the island of Cuba, Maj. Gen. Leonard Wood, 
United States Volunteers, without whose approval and assistance 
these observations could not have been carried out. 

In order to exercise perfect control over the movements of those 
individuals who were to be subjected to experimentation, and to 
avoid any other possible source of infection, a location was selected 
in an open and uncultivated field, about 1 mile from the town of 
Quemados, Cuba. Here an experimental sanitary station was estab- 
lished under the complete control of the senior member of this board. 
This station was named Camp Lazear, in honor of our late colleague, 
Dr. Jesse W. Lazear, acting assistant surgeon, United States Army, 
who died of yellow fever, while courageously investigating the 
causation of this disease. The site selected was very well drained, 
freely exposed to sunlight and winds', and, from every point of view, 
satisfactory for the purposes intended. 

« Read at the Pan Am. Med. Cong., held in Habana, Cuba, Feb. 4-7, 1901. 
2 Phila. Med. Jour., Oct. 27, 1900. 
70 



YELLOW FEVER. 71 

The personnel of this camp consisted of two medical officers, Dr. 
Roger P. Ames, acting assistant surgeon, United States Army, an 
immune; in immediate charge; Dr. R. P. Cooke, acting assistant 
surgeon, United States Army, nonimmune; one acting hospital 
steward, an immune ; nine privates of the hospital corps, one of whom 
was immune; and one immune ambulance driver. 

For the quartering of this detachment, and of such nonimmune 
individuals as should be received for experimentation, hospital tents, 
properly floored, were provided. These were placed at a distance of 
about 20 feet from each other, and were numbered 1 to 7, respectively. 

Camp Lazear was established November 20, 1900, and from this 
date was strictly quarantined, no one being permitted to leave or 
enter camp except the three immune members of the detachment 
and the members of the board. Supplies were drawn chiefly from 
Columbia Barracks, and for this purpose a conveyance under the con- 
trol of an immune acting hospital steward, and having an immune 
driver, was used. 

A few Spanish immigrants, recently arrived at the port of Habana, 
were received at Camp Lazear, from time to time, while these observa- 
tions were being carried out. A nonimmune person, having once left 
this camp, was not permitted to return to it under any circumstances 
whatever. 

The temperature and pulse of all nonimmune residents were care- 
fully recorded three times a day. Under these circumstances any 
infected individual entering the camp could be promptly detected and 
removed. As a matter of fact only two persons, not the subject of 
experimentation, developed any rise of temperature; one, a Spanish 
immigrant, with probably commencing pulmonary tuberculosis, who 
was discharged at the end of three days; and the other, a Spanish 
immigrant, who developed a temperature of 102.6° F. on the after- 
noon of his fourth day in camp. He was at once removed with his 
entire bedding and baggage and placed in the receiving ward at Colum- 
bia Barracks. His fever, which was marked by daily intermissions 
for three days, subsided on the administration of cathartics and ene- 
mata. His first attack was considered to be due to intestinal irrita- 
tion. He was not permitted, however, to return to the camp. 

No nonimmune resident was subjected to inoculation who had not 
passed in this camp the full period of incubation of yellow fever, with 
one exception, to be hereinafter mentioned. 

OBSERVATIONS. 

Having thus sufficiently indicated the environment of Camp 
Lazear and the conditions under which its residents lived, we will 
now proceed to a narration of the observations thus far made at this 
experimental station. At the time these inoculations were begun, 
the several tents were occupied as follows: Tent No. 1 by one im- 
mune and one nonimmune; No. 2 by one immune and two non- 
immunes; No. 3 by two immunes; No. 4 by three nonimmunes; 
No. 5 by three nonimmunes; No. 6 by two nonimmunes; and No. 7 
by one nonimmune. 

For the purpose of experimentation, subjects were selected as 
follows: From tent No. 2, two nonimmunes, and from tent No. 5, 
three nonimmunes. Later, one nonimmune in tent No. 6 was also 
designated for inoculation. 



■72 



YELLOW FEVEE. 




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74 YELLOW FEVER. 

Case 1. — Pvt. John R. Kissinger, Hospital Corps, United States Army, aged 23, a 
nonimmune, occupant of tent No. 2, with his full consent, was bitten at 10.30 a. m., 
November 20, 1900, by a mosquito (C. fasciatus) that had bitten a severe case of 
yellow fever on the fifth day, 11 days previously; another severe case, on the third 
day, 6 days before ; and a third severe one on the third day, 3 days before. As Kissinger 
had not absented himself from Columbia Barracks for a period of more than 30 days, it 
was considered safe to inoculate him without waiting for his period of incubation to 



November 23, 1900, Kissinger was again bitten by the same mosquito. The result 
of both inoculations was negative. The mosquito, therefore, was incapable of convey- 
ing any infection on the eleventh or fourteenth day after it had bitten a severe case 
of yellow fever on the third day of the disease. This insect had been kept at ordinary 
room temperature and died November 26, 1900. 

December 5, 1900, at 2 p. m., 12 days after the last inoculation, Kissinger was again 
bitten by 5 mosquitoes (C. fasciatus), 2 of which had bitten fatal cases of yellow fever, 
1 the second day, 15 days before; 1 a severe case on the second day, 19 days previously, 
and 2 a mild case on the third day, 21 days before. 

The record of temperature and pulse, taken every 3 hours following this inoculation, 
showed that the subject remained in his usual state of health during the following 3 
days, except that on December 8, on the third day, Kissinger had slight vertigo upon 
rising, which soon passed away. At 4.30 p. m. — commencement of fourth day — he 
complained of frontal headache; otherwise he felt well and partook of supper with 
appetite; at 9 p. m., temperature was 98.4° F., pulse 90; at 11.30 p. m., he awoke 
with a chill, his temperature 100° F.. pulse 90; he complained of severe frontal head- 
ache and backache; his eyes were injected and his face suffused. December 9 at 3 
a. m., his temperature was 102° F., pulse 102; he had violent headache and backache, 
with nausea and vomiting. He was then removed to the yellow-fever wards. His 
subsequent history was that of a case of yellow fever at moderate severity. Albumin 
appeared in the urine on the fourth day, increased to one-fifth by volume on the sixth 
day, and disappeared on December 22. Granular casts were present in considerable 
numbers from the fourth to the eighth day. The conjunctivae were jaundiced on the 
third day. The diagnosis of yellow fever in this case was made by Drs. Juan Guiteras, 
Carlos Finlay, W. C. Gorgas, and A. Diaz Albertini, the board of yellow-fever experts 
of the city of Habana , who saw the patient on several occasions during his illness. (See 
Chart I. ) The period of incubation in this case was 3 days, 9£ hours. 

Case 2. — John J. Moran, aged 24, an American, nonimmune, occupant of tent No. 2, 
with his full consent, was bitten at 10 a. m., November 26, 1900, by a mosquito (C. 
fasciatus) which 12 days before had bitten a case of yellow fever of moderate severity, 
on the third day of the disease. This insect had also bitten a well-marked case of 
yellow fever — second day — 10 days previously. 

November 29, at 2.20 p. m., Moran was again bitten by the same mosquito. The 
result of both of these inoculations was negative. This insect was therefore incapable 
of conveying the infection 15 days after having bitten a case of yellow fever of mod- 
erate severity on the third day, and 13 days after it had bitten a well-marked case of 
this disease on the second day. This mosquito had been kept at room temperature. 
Moran's case will be again referred to when we come to speak of the infection of a 
building by means of contaminated mosquitoes. 

Case 3. — A Spanish immigrant, aged 26, a nonimmune occupant of tent No. 5, with 
his full consent, was bitten at 4 p.m., December 8, 1900, by 4 mosquitoes ( C. fasciatus) 
which had been contaminated as follows: One by biting a fatal case of yellow fever, 
on the third day, 17 days before; 1 a severe case, on the third day, 18 days before; 1 
a severe case, on the second day, 22 days before, and 1 a case of moderate severity, 
on the third day, 24 days previously. 

The record of temperature and pulse, taken every 3 hours after the inoculation, shows 
no rise of temperature above 99° F. until 6 p. m., December 13, on the sixth day, 
when 99.4° F. is recorded; pulse, 68. The subject, who was of a very lively disposi- 
tion, retained his usual spirits until noon of the 13th, although he complained of slight 
frontal headache on the 11th and 12th. He took to his bed at noon of the 13th, the 
fifth day, complaining of increased frontal headache and a sense of fatigue. At 9 
p. m., his temperature was 98.2° F., pulse 62. 

December 14, at 6 a. m., temperature was 98° F., pulse 72, and he still complained 
of frontal headache and general malaise. Profuse epistaxis occurred at 7.45 a. m. ; at 
9 a. m., temperature was 99.6° F., pulse 80; at 1.15 p. m., temperature was 100° F., 
pulse 80, and he complained of a sense of chillness, with frontal headache increased, 
and slight pain in the back, arms, and legs; at 3 p.m., temperature was 100 ° F. , pulse 
80; at 4.15 p. m., temperature 100.7° F., pulse 68; his face flushed and eyes congested. 
He was removed to the vellow-fever wards. A trace of albumin was found in the urine 



YELLOW FEVEB. 75 

passed at 3.30 p. m., December 15; a few hyaline cases were present. He was seen 
at this time by the Habana board of experts, and the diagnosis of mild yellow fever 
confirmed. (See Chart Xo. 2.) 

The period of incubation in this case was 4 days and 24 hours, counting from the 
time of inoculation to the hour when the patient took to his bed; if reckoned to the 
onset of fever, it was 5 days and 17 hours. 

Case 4- — A Spanish i mmi grant, aged 27, a nonimmune occupant of tent Xo. 5, 
with his full consent, was bitten at lO a. m. Xovember 26, 1900, by a mosquito (C. 
fasciatus) which had bitten a severe case of yellow fever on the second day 10 days 
before. Three days later, Xovember 29, he was again bitten by the same insect. 
December 2, after an interval of 3 days, he was again bitten by the same insect. 
and also by a second mosquito ( C. fasciatus) which 12 days before had been con- 
taminated by biting a fatal case of yellow fe\-er on the third day. N o unfavorable 
effects followed any of these attempted inoculations. The first-mentioned mosquito. 
therefore, was incapable of conveying any infection on the seventeenth day after 
biting a severe case of yellow fever on the second day; the other also failed to' infect 
on the twelfth day after biting a fatal case of yellow fever on the third day. Both 
of these mosquitoes had been kept at ordinary room temperature. 

December 9, after an interval of 7 days, the subject was again bitten, at 10.30 a. m.. 
by 1 mosquito (C. fasciatus) which had been infected 19 days before by biting a 
fatal case of yellow fever on the second day of the disease. He remained in his usual 
health until 9 a. m. December 12, the third day, when he complained of frontal 
headache; his temperature was 98.8° F., pulse 96. This headache continued during 
the entire dav. At 6 p. m. temperature was 99° F., pulse 94; at 9 p. m. tempera- 
ture 99° F., pulse 84; at 9.30 p. m. temperature 99.4° F.. pulse 82. Severe head- 
ache and backache was complained of; his eyes were injected and his face suffused. 
The following morning he was sent to the yellow-fever wards. Urine passed at 4.20 
p. m. December 15, the third day. gave a distinct trace of albumin. Many hyaline 
casts were present on the same date. The conjunctivae were jaundiced on the third 
day. 

The patient was seen by the board of experts on December 14 and the diagnosis 
of yellow fever made. (See Chart No. 3.) 

The period of incubation in this case was 3 days 11? hours. 

Case 5. — A Spanish immigrant, aged 20. a nonimmune occupant of -tent Xo. 5. 
with his full consent, was bitten at 10 a. m. Xovember 26. 1900. by a mosquito (C. 
fasciatus) that had bitten a well-marked case of yellow fever on the third day 12 
days before. November 29 he was again bitten by the same insect. December 2 
he was for the third time bitten by 2 mosquitoes ( C. fasciatus), both of which had 
bitten a well-marked case of yellow fever on the third day. iS days before. As no 
bad results followed any of these inoculations, it follows that these mosquitoes were 
incapable of conveying any infection 18 days after they had bitten a well-marked 
case of yellow fever on the third day. Both of these insects had been kept at room 
temperature. 

December 11. after an interval of 9 days, the subject was again, at 4.30 p. m.. bitten 
by the same mosquitoes, 4 in number, that had been applied to case 3 three days prior 
to this time, with positive results. 

The record of temperature and pulse, taken every 3 hours following the inoculation, 
showed no change till December 13, the second day, at 9 a. m.. when the temperature 
was 99° F., and the pulse 78. From this hour till 6 p. m. the temperature varied from 
99.2° to 99.6° F. The subject complained of frontal headache, slight in degree, 
during the entire day. At 9 p. m. his temperature was 98.4° F., pulse 62. • 

December 14, the third day, he complained of slight frontal headache during the 
entire day, and was indisposed to exertion. From 6 a. m. to 6 p. m. the temperature 
averaged*99.2° F., and the pulse varied from 64 to 90; at 9 p. m. it was 98.4° F., the pulse 
78. December 15, the fourth day, at 6 a. m. temperature was 98.2° F., pulse 78. 
He still had frontal headache. At 9 a. m. temperature was 99.2° F., pulse 80; at 12, 
noon, the former was 99.2° F., the pulse 74. The subject now went to bed, complaining 
of headache and pains throughout the body. At 2 p. m. the temperature was 100° F., 
the pulse 80; eyes much congested; face flushed. At 6 p. m. his temperature had risen 
to 102° F., and the pulse to 90. He was then transferred to the yellow fever wards. 
Albumin appeared in the urine at 7.30 a. m., December 17. Bleeding from the gums 
and roof of the mouth occurred on the sixth and seventh days of his illness. 

The case was examined by the board of experts on the 16th and 19th, and the diag- 
nosis of yellow fever made. 

Albumin disappeared on the sixth day, the temperature falling to normal on this 
date, and remaining near this point till December 23, the ninth day of sickness, 
when a relapse occurred, attended with bleeding from the gums on December 24 



76 



YELLOW FEVER. 



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YELLOW EEVEE. 




YELLOW FEVER. 



79 




80 YELLOW FEVER. 

and 25, with the appearance of red blood cells and pus cells in the urine in moderate 
numbers. Fever subsided on December 26, and the urine became normal on December 
29. (See Chart 4.) 

The period of incubation in this case, if reckoned from the time of inoculation to 
the hour when the patient took to his bed, was 3 days, 194 hours. 

The four patients whose histories we have given above were also 
examined by a number of physicians of Habana, among whom we may 
mention Dr. Bango, of "La Covadonga," Dr. Sanchez, of "La Bene- 
fica," and Dr. Moas, of "La Purissima Concepcion," by all of whom 
the diagnosis of yellow fever was confirmed. Let us now rapidly 
review the circumstances attending these cases of experimental yellow 
fever, in order to emphasize certain points of interest and importance 
in connection with their occurrence. (We omit any reference to the 
clinical histories.) 

It should be borne in mind that at the time when these inoculations 
were begun there were only 12 nonimmune residents at Camp Lazear, 
and that 5 of these were selected for experiment, viz, 2 in tent No. 2 
and 3 in tent No. 5. Of these we succeeded in infecting 4, viz, 1 in 
tent No. 2 and 3 in tent No. 5, each of whom developed an attack of 
yellow fever within the period of incubation of this disease. The one 
negative result, therefore, was in case 2 — Moran — inoculated with a 
mosquito on the fifteenth day after the insect had bitten a case of 
yellow fever on the third day. Since this mosquito failed to infect 
case 4, three days after it had bitten Moran, it follows that the result 
could not have been otherwise than negative in the latter case. We 
now know, as the result of our observations, that in the case of an 
insect kept at room temperature during the cool weather of November, 
15 or even 18 days would, in all probability, be too short a time to 
render it capable of producing the disease. 

As bearing on the source of infection, we invite attention to the 
period of time during which the subjects had been kept under rigid 
quarantine, prior to successful inoculation, which was as follows: 
Case 1, 15 days; case 3, 9 days; case 4, 19 days; case 5, 21 days. 
We further desire to emphasize the fact that this epidemic of yellow 
fever, which affected 33.33 per cent, of the nonimmune residents of 
Camp Lazear, did not concern the 7 nonimmunes occupying tents 
No. 1, 4, 6, and 7, but was strictly limited to those individuals who 
had been bitten by contaminated mosquitoes. 

Nothing could point more forcibly to the source of this infection 
than the order of the occurrence of events at this camp. The pre- 
cision with which the infection of the individual followed the bite of 
the mosquito left nothing to be desired in order to fulfill the require- 
ments of a scientific experiment. 

The epidemic having ceased on December 15, 1900, no other case 
of yellow fever occurred in this camp until we again began to expose 
individuals to inoculation. Thus 15 days later we made the following 
observation: 

Case 6. — A Spanish immigrant, aged 27, a nonimmune occupant of tent No. 6, with 
his full consent, was bitten at 11 a. m., December 30, 1900, by 4 mosquitoes (C. fascia- 
tus) that had been contaminated 17 days previously by biting a mild case of yellow 
fever on the first day of the disease (case 4). These insects had been kept at a tem- 
perature of 82° F. 

The subject remained in his normal condition until the evening of January 2, 1901, 
the third day, when he complained of frontal headache. At 6 p.-m., his temperature 
was 99° F., pulse 64. He slept well, but still complained of headache on the following 
morning, January 3. He partook sparingly of breakfast, and afterwards lay on his bed, 



YELLOW FEVER. 81 

being disinclined to exert himself. At 9 a. m., the temperature was 99° F., the pulse 
96; at 10.30 a. m., temperature 100° F., pulse 80. A sense of chilliness and sharp 
frontal headache was complained of, and at 3 p. m. his temperature was 100.8° F., his 
pulse 89, and his eyes were congested and face flushed. He was removed to the 
yellow-fever wards. A specimen of urine passed at midnight, January 4, contained a 
distinct trace of albumin. Slight bleeding from the gums occurred on the fifth and 
sixth days. The patient was seen by the board of experts on the second and seventh 
days of his attack, and the diagnosis of yellow fever confirmed. (See Chart 5.) 

The period of incubation in this case was 3 days. 22^ hours. The subject had 
remained in strict quarantine for 22 days preceding his inoculation. 

In considering the character of the attacks and the course of the 
disease in these five cases of experimental yellow fever, it must be 
borne in mind that these infected individuals were all young men, in 
good general physical condition and placed amid excellent hygienic 
surroundings. Further, it must not be forgotten that, on the earliest 
manifestation of an approaching infection, they were each and all put 
to bed at once, and were even carried to the yellow-fever wards while 
occupying the same bed. In other words, these men were kept at 
absolute rest from the first inception of the disease. Just what bear- 
ing this may have had on the subsequent course of the fever, we can 
not say, but since so much stress is laid on absolute rest of the patient 
by those having most experience in the treatment of yellow fever, the 
influence of this enforced rest, in our case, upon the subsequent 
course of the attack, was doubtless of much importance. We reserve 
a consideration of the clinical side of these cases for a future report. 

In our opinion, the experiments above described conclusively 
demonstrate that an attack of yellow fever may be readily induced 
in the healthy subject by the bite of mosquitoes {C.fasciatus) which 
have been previously contaminated by being fed with the blood of 
those sick with yellow fever, provided the insects are kept for a suffi- 
cient length of time after contamination before being applied to the 
person to be infected. 

Our observations do not confirm Finlay's statement that the bite 
of the mosquito may confer an abortive attack of yellow fever when 
applied to the healthy subject 2 to 6 days after it has bitten a yellow 
fever patient. We have always failed to induce an attack even of 
the mildest description when we have used mosquitoes within less 
than 12 days from the time of contamination, although the insects 
were constantly kept at summer temperature. We could cite 
instances where we have applied mosquitoes at intervals of 2, 3, 4, 
5, 6, 9, and 11 days following the contamination of the insect with 
the blood of well-marked cases of yellow fever early in the disease 
without any effect whatever being produced by the bite. Thus in 1 
case no result followed the bite of 14 mosquitoes which 4 days pre- 
viously had been contaminated by biting a case of yellow fever on 
the first day. Again, 7 da} T s later, or 11 da} r s after contamination, 
the surviving 7 of these insects failed to infect an individual. On 
the seventeenth day after contamination, however, the bite of 4 of 
these mosquitoes — all that remained of the original 14 — was promptly 
followed by an attack of yellow fever in the same individual. These 
insects had been kept during the whole of this time at an average 
temperature of 82° F. 

Our observations would seem to indicate that after the parasite 
has been taken into the mosquito's stomach, a certain number of 
days must elapse before the insect is capable of reconveying it to man. 

79965°— S. Doc. 822. 61-3 6 



82 YELLOW FEVBK. 

This period doubtless represents the time required for the parasite 
to pass from the insect's stomach to its salivary glands, and would 
appear to be about 12 days in summer weather and most probably 
about 18 or more days during the cooler winter months. It follows 
also that our observations do not confirm Finlay's opinion that the 
bite of the contaminated mosquito may confer immunity against a 
subsequent attack of yellow fever. In our experience an individual 
may be bitten on three or more occasions by contaminated mosquitoes 
without manifesting any symptoms of disturbance to health, and yet 

Eromptly sicken with yellow fever within a few days after being 
itten by an insect capable of conveying the infection. 

ACQUIREMENT OF THE DISEASE. 

Having shown that yellow fever can be conveyed by the bite of 
an infected mosquito, it remains to inquire whether this disease 
can be acquired in any other manner. It has seemed to us that 
yellow fever, like the several types of malarial fever, might be induced 
by the injection of blood taken from the general circulation of a 
patient suffering from this disease. Accordingly we have subjected 
four individuals to this method of infection, with one negative and 
three positive results. Reserving the detailed description of these 
cases to a subsequent occasion, we may state that in one of the posi- 
tive cases an attack of pronounced yellow fever followed the subcu- 
taneous injection of 2 c. c. of blood taken from a vein at the bend of 
the elbow on the first day of the disease, the period of incubation 
being 3 days and 22 hours; in the second case, 1.5 c. c. of blood, taken 
on the first day of the disease and injected in the same manner, 
brought about an attack within 2 days and 12 hours; while in our 
third case, the injection of 0.5 c. c. of blood, taken on the second day 
of the disease, produced an attack at the end of 41 hours. 

In the case mentioned as negative to the blood injection, the sub- 
sequent inoculation of this individual with mosquitoes already proved 
to be capable of conveying the disease, also resulted negatively. We 
think, therefore, that this particular individual, a Spanish immigrant, 
may be considered as one who probably possesses a natural immunity 
to yellow fever. 

It is important to note that in the three cases in which the injection 
of the blood brought about an attack of yellow fever, careful cultures 
from the same blood, taken immediately after injection, failed to 
show the presence of Sanarelli's bacillus. 1 

Our observations, therefore, show that the parasite of yellow fever 
is present in the general and capillary circulation, at least during the 
early stages of this disease, and that the latter may be conveyed, like 
the malarial parasite, either by means of the bite of the mosquito or 
by the injection of blood taken from the general circulation. 

1 A fourth case of yellow fever, severe in type, has been produced by the subcutaneous injection of 1 c. c. 
of blood taken from the general circulation on the second day of the disease, the period of incubation being 
3 days and 1 hour. The patient from whom the blood was obtained was an experimental case which was 
in turn produced by the injection of blood — 0.5 c. c. — derived from a nonexperimental case of fatal yellow 
fever. As "controls," cases 1, 4, 6, and 7 of this report were also injected subcutaneously with 1 c. c. of 
the same blood without manifesting any symptoms whatever. The blood which produced this fourth 
case of yellow fever, when transferred at the same time to bouillon tubes in considerable quantities, gave no 
growth whatever, 



YELLOW FEVER. 83 

CAN YELLOW FEVER BE PROPAGATED IN ANY OTHER WAY ? 

We believe that the general consensus of opinion of both the medical 
profession and the laity is strongly in favor of the conveyance of 
yellow fever by fomites. The origin of epidemics, devastating in 
their course, has been frequently attributed to the unpacking of 
trunks and boxes that contained supposedly infected clothing; and 
hence the efforts of health authorities, both State and National, are 
being constantly directed to the thorough disinfection of all clothing 
and bedding snipped from ports where yellow fever prevails. To 
such extremes have efforts at disinfection been carried, in order to 
prevent the importation of this disease into the United States, that 
during the epidemic season all articles of personal apparel and bedding 
have been subjected to disinfection, sometimes both at the port of 
departure and at the port of arrival; and this has been done whether 
the articles have previously been contaminated by contact with 
yellow fever patients or not. The mere fact that the individual has 
resided, even for a day, in a city where yellow fever is present, has 
been sufficient cause to subject his baggage to rigid disinfection by 
the sanitary authorities. 

To determine, therefore, whether clothing and bedding, which 
have been contaminated by contact with yellow fever patients and 
their discharges, can convey this disease is a matter of the utmost 
importance. Although the literature contains many references to 
the failure of such contaminated articles to cause the disease, we have 
considered it advisable to test, by actual experiment on nonimmune 
human beings, the theory of the conveyance of yellow fever by 
fomites, since we know of no other way in which this question can 
ever be finally determined. 

For this purpose there was erected at Camp Lazear a small frame 
house consisting of one room 14 by 20 feet, and known as "Building 
No. 1," or the ''Infected clothing and bedding building." The cubic 
capacity of this house was 2,800 feet. It was tightly ceiled within 
with "tongue and grooved" boards, and was well battened on the 
outside. It faced to the south and was provided with two small 
windows, each 26 by 34 inches in size. These windows were both 
placed on the south side of the building, the purpose being to prevent, 
as much as possible, any thorough circulation of the air within the 
house. They were closed by permanent wire screens of 0.5 mm. 
mesh. In addition sliding glass sash were provided within and heavy 
wooden shutters without; the latter intended to prevent the entrance 
of sunlight into the building, as it was deemed undesirable that the 
disinfecting qualities of sunlight, direct or diffused, should at any 
time be exerted on the articles of clothing contained within this room. 
Entrance was effected through a small vestibule, 3 by 5 feet, also 
placed on the southern side of the house. This vestibule was pro- 
tected without by a solid door and was divided in its middle by a 
wire screen door, swung on spring hinges. The inner entrance was 
also closed by a second wire screen door. In this way the passage 
of mosquitoes into this room was effectually excluded. During 
the day, and until after sunset, the house was kept securely closed, 
while by means of a suitable heating apparatus the temperature was 
raised from 92° to 95° F. Precaution was taken at the same time to 
maintain a sufficient humidity of the atmosphere. The average 



84 YELLOW FEVER. 

temperature of this house was thus kept at 76.2° F. for a period 
of 63 days. 

November 30, 1900, the building now being ready for occupancy, 
three large boxes rilled with sheets, pillow slips, blankets, etc., con- 
taminated by contact with cases of yellow fever and their discharges 
were received and placed therein. The majority of the articles had 
been taken from the beds of patients sick with yellow fever at Las 
Animas Hospital, Habana, or at Columbia Barracks. Many of them 
had been purposely soiled with a liberal quantity of black vomit, 
urine, and fecal matter. A dirty " comfortable" and much-soiled 
pair of blankets, removed from the bed of a patient sick with yellow 
fever in the town of Quemados, were contained in one of these boxes. 
The same day, at 6 p. m., Dr. R. P. Cooke, acting assistant surgeon, 
United States Army, and two privates of the Hospital Corps, all non- 
immune young Americans, entered this building and deliberately 
unpacked these boxes, which had been tightly closed and locked for 
a period of two weeks. They were careful at the same time to give 
each article a thorough handling and shaking in order to disseminate 
through the air of the room the specific agent of yellow fever, if con- 
tained in these fomites. These soiled sheets, pillow cases, and 
blankets were used in preparing the beds in which the members of 
the Hospital Corps slept. Various soiled articles were hung around 
the room and placed about the bed occupied by Dr. Cooke. 

From this date until December 19, 1900, a series of 20 days, this 
room was occupied each night by these three nonimmunes. Each 
morning the various soiled articles were carefully packed in the afore- 
said boxes, and at night again unpacked and distributed about the 
room. During the day the residents of this house were permitted to 
occupy a tent pitched in the immediate vicinity, but were kept in 
strict quarantine. 

December 12, a fourth box of clothing and bedding was received 
from Las Animas Hospital. These articles had been used on the beds 
of yellow-fever patients, but in addition had been purposely soiled 
with the bloody stools of a fatal case of this disease. As this box 
had been packed for a number of days, when opened and unpacked 
by Dr. Cooke and his assistants, on December 12, the odor was so 
offensive as to compel them to retreat from the house. They pluckily 
returned, however, within a short time and spent the night as usual. 

December 19, these three nonimmunes were placed in quarantine 
for 5 days and then given the liberty of the camp. All had remained 
in perfect health, notwithstanding their stay of 20 nights amid such 
unwholesome surroundings. 

During the week, December 20-27, the following articles were also 
placed in this house, viz: Pajama suits, 1 ; undershirts, 2; nightshirts, 
4; pillow slips, 4; sheets, 6; blankets, 5; pillows, 2; mattresses, 1. 
These articles had been removed from the persons and beds of four 
patients sick with yellow fever and were very much soiled, as any 
change of clothing or bed linen during their attacks had been pur- 
posely avoided, the object being to obtain articles as thoroughly 
contaminated as possible. 

From December 21, 1900, till January 10, 1901, this building was 
again occupied by two nonimmune young Americans under the same 
conditions as the preceding occupants, except that these men slept 



YELLOW FEVER. 85 

every night in the very garments worn by yellow-fever patients 
throughout their entire attacks, besides making use exclusively of 
their much-soiled pillow slips, sheets, and blankets. At the end of 
21 nights of such intimate contact with these fomites, they also went 
into quarantine, from which they were released 5 days later in per- 
fect health. 

From January 11 till January 31, a period of 20 days, "Building 
No. 1" continued to be occupied by two other nonimmune Amer- 
icans, who, like those who preceded them, have slept every night in 
the beds formerly occupied by yellow-fever patients and in the night- 
shirts used by these patients throughout the attack, without change. 
In addition, during the last 14 nights of their occupancy of this house, 
they have slept, each night, with their pillows covered with towels 
that had been thoroughly soiled with the blood drawn from both the 
general and capillary circulation, on the first day of the disease, in 
the case of a well-marked attack" of yellow fever. Notwithstanding 
this trying ordeal, these men have continued to remain in perfect 
health. 

The attempt which we have therefore made to infect "Building 
No. 1 " and its 7 nonimmune occupants, during a period of 63 days, 
has proved an absolute failure. We think we can not do better here 
than to quote from the classic work of La Roche. 1 Tins author says: 

In relation to the j^ellow fever, we find so many instances establishing the fact of the 
nontransmissibliity of the disease through the agency of articles of the kind mentioned, 
and of merchandise generally, that we can not but discredit the accounts of a contrary 
character assigned in medical writings, and still more to those presented on the strength 
of popular report solely. For if in a large number of well authenticated cases such 
articles have been handled and used with perfect impunity — and that, too, often under 
circumstances best calculated to insure the effect in question — we have every reason 
to conclude that a contrary result will not be obtained in other instances of a similar 
kind, and that consequently the effect said to have been produced by exposure to those 
articles must — unless established beyond the possibility of doubt — be referred to some 
other agency. 

The question here naturally arises: How does a house become 
infected with yellow fever? This we have attempted to solve by 
the erection at Camp Lazear of a second house, known as "Building 
No. 2, ,; or the "Infected mosquito building/' This was in all 
respects similar to "Building No. 1/' except that the door and 
windows were placed on opposite sides of the building so as to give 
through-and-through ventilation. It was divided, also, by a wire- 
screen partition, extending from floor to ceiling, into two rooms, 
12 by 14 feet and 8 by 14 feet, respectively. Whereas, all articles 
admitted to "Building No. 1" have been soiled by contact with 
yellow-fever patients, all articles admitted to "Building No. 2" were 
first carefully disinfected by steam before being placed therein. 

On December 21, 1900, at 11.45 a. m., there were set free in the 
large room of this building 15 mosquitoes (C. fasciatus) which had 
previously been contaminated by biting yellow -fever patients, as 
follows: One, a severe case, on the second day, November 27, 1900, 
24 days; 3, a well-marked case, on the first day, December 9, 1900, 
12 days; 4, a mild case, on the first day, December 13, 1900, 8 days; 
7, a well-marked case, on the first day, December 16, 1900, 5 days — 
total, 15. 

1 R. La Roche: Yellow Fever, Vol. II, p. 516, Philadelphia. 



86 YELLOW FEVER. 

Only one of these insects was considered capable of conveying the 
infection, viz, the mosquito that had bitten a severe case 24 days 
before, while 3 others — the 12-day insects — had possibly reached the 
dangerous stage, as they had been kept at an average temperature 
of 82° F. 

At 12 M. of the same day, John J. Moran — already referred to 
as Case 2 in this report, a nonimmune American, entered the room 
where the mosquitoes had been freed and remained 30 minutes. 
During this time he was bitten about the face and hands by several 
insects. At 4.30 p. m., the same day, he again entered and remained 
20 minutes, and was again bitten. The following day, at 4.30 p. m., 
he, for the third time, entered the room and was again bitten. 

Case 7. — On December 25, 1900, at 6 a. m., the fourth day, Moran complained of 
slight dizziness and frontal headache. At 11 a. m. he went to bed, complaining of 
increased headache and malaise, with a temperature of 99.6° F., pulse 88; at noon the 
temperature was 100.4° F., the pulse 98; at 1 p. m., 101.2° F., the pulse 96, and his 
eyes were much injected and face suffused. He was removed to the yellow fever 
wards. He was seen on several occasions by the board of experts and the diagnosis of 
yellow fever confirmed. (See Chart 6.) 

The period of incubation in this case, dating from the first visit to 
"Building No. 2," was 3 days and 23 hours. If reckoned from his 
last visit it was 2 days and 18 hours. There was no other possible 
source for his infection, as he had been strictly quarantined at Camp 
Lazear for a period of 32 days prior to his exposure in the mosquito 
building. 

During each of Moran's visits, two nonimmunes remained in this 
same building, only protected from the mosquitoes by the wire-screen 
partition. From December 21, 1900, till January 8, 1901, inclusive — 
18 nights — these nonimmunes have slept in this house, only protected 
by the wire-screen partition. These men have remained in perfect 
health to the present time. 

December 28, after an interval of 7 days, this house was again 
entered by a nonimmune American, who remained 25 minutes. The 
subject was bitten by only one insect. The following day he again 
entered and remained 15 minutes, and was again bitten by one 
mosquito. The result of these two visits was entirely negative. As 
the mortality among the insects in this room, from some unknown 
cause, had been surprisingly large, it is possible that the subject was 
bitten by insects not more than 13 days old, in which case they would 
probably not infect, since they had been kept for only 5 days at a tem- 
perature of 82° F., and for 8 days at the mean temperature of the 
room, 78° F. 

Be this as it may, nothing can be more striking or instructive as 
bearing upon the cause of house infection in yellow fever than when 
we contrast the results obtained in our attempts to infect Buildings 
No. 1 and No. 2; for whereas in the former all of 7 nonimmunes 
escaped the infection, although exposed to the most intimate contact 
with the fomites for an average period of 21 nights each, in the latter 
an exposure, reckoned by as many minutes, was quite sufficient to 
give an attack of yellow fever to one out of two persons who entered 
the building — 50 per cent. 

Thus, at Camp Lazear, of 7 nonimmunes whom we attempted to 
infect by means of the bites of contaminated mosquitoes, we have 
succeeded in conveying the disease to 6, or 85.71 per cent. On the 



YELLOW FEVER. S7 

other hand, 7 nonimmunes whom we tried to infect by means of 
fomites, under particularly favorable circumstances, we did not 
succeed in a single instance. Out of a total of 18 nonimmunes whom 
we have inoculated with contaminated mosquitoes since we began 
this line of investigation, 8, or 44.4 per cent, have contracted yellow 
fever. If we exclude those individuals bitten by mosquitoes that 
had been kept less than 12 days after contamination, and which were, 
therefore, probably incapable of conveying the disease, we have to 
record 8 positive and 2 negative results — 80 per cent. 

CONCLUSIONS. 

1. The mosquito (C. fasciatus) serves as the intermediate host for 
the parasite of yellow fever. 

2. Yellow fever is transmitted to the nonimmune individual by 
means of the bite of the mosquito that has previously fed on the 
blood of those sick with this disease. 

3. An interval of about 12 days or more after contamination 
appears to be necessary before the mosquito is capable of conveying 
the infection. 

4. The bite of the mosquito at an earlier period after contamina- 
tion does not appear to confer any immunity against a subsequent 
attack. 

5. Yellow fever can also be experimentally produced by the sub- 
cutaneous injection of blood taken from the general circulation 
during the first and second days of this disease. 

6. An attack of yellow fever, produced by the bite of the mosquito, 
confers immunity against the subsequent injection of the blood of an 
individual suffering from the nonexperimental form of this disease. 

7. The period of incubation in 13 cases of experimental yellow 
fever has varied from 41 hours to 5 days and 17 hours. 

8. Yellow fever is not conveyed by fomites, and hence disinfection 
of articles of clothing, bedding, or merchandise, supposedly contam- 
inated by contact with those sick with this disease, is unnecessary. 

9. A house may be said to be infected with yellow fever only when 
there are present within its walls contaminated mosquitoes capable 
of conveying the parasite of this disease. 

10. The spread of yellow fever can be most effectually controlled 
by measures directed to the destruction of mosquitoes and the pro- 
tection of the sick against the bites of these insects. 

11. While the mode of propagation of yellow fever has now been 
definitely determined, the specific cause of this disease remains to be 
discovered. 

DISCUSSION. 

Dr. Louis Perna, Cienfuegos, Cuba, in opening the discussion, said 
that it is sophism to believe that post hoc, ergo propter hoc; that is to 
say, that, as Carmona, Freire, Sanarelli, and others have fallen to 
this error, we must not be too precipitate in accepting the result 
of statistics. The studies made of mosquitoes are very old. A 
French physician, who died about 1850, expressed the opinion that 
malaria, yellow fever, and cholera were propagated by mosquitoes. 
Dr. Perna also criticized the methods employed by the commission 



88 YELLOW FEVER. 

in making experiments on human beings and is entirely opposed to 
such experiments. 

Dr. San Martin eloquently defended, and with strong arguments, 
the high scientific standard of the experiments as carried out by this 
commission, and also brought out the point that it was not statistics 
but facts that this commission presented. 

Dr. H. B. Horlbeck, Charleston, S. C, expressed his opinion that 
the problem of 200 years was about to be solved, that the old quar- 
antine regulations should be greatly modified. He also described 
the existence of a pine belt within a short distance of Charleston, 
S. C, in which yellow fever never developed as an epidemic, although 
the afflicted therewith would go there during the existence of the 
epidemic in Charleston, would die from the disease, and yet it would 
not spread. Mosquitoes are not known in that region, and probably 
this is the true explanation of the above fact. He concluded by 
emphasizing the inestimable value of these experiments if they prove 
to be true. 

Dr. Emilio Martinez, Habana, laid emphasis on Dr. San Martin's 
views. He took up the moral question and claimed that without 
these no truth could have been found. 

Dr. Manuel Gutierrez, Mexico, who up to within a short time had 
been adverse to the theory of the transmission of this disease by 
mosquitoes, now accepted as incontrovertible the results of the experi- 
ments of the commission. He followed with interest many of the 
experiments, and as a member of the commission saw most of these 
cases, which he had no hesitation in pronouncing typical cases of 
yellow fever. A fact which impressed him forcibly was the absolute 
control of the epidemic by Dr. Reed. The cases would develop or 
not, as he wished. He does not think that the mosquito should be 
called the Culex fasciatus. Giles's description of the Culex tiniads 
mosquito agrees more closely than with the Culex fasciatus. He 
describes the difference between them. He is inclined to consider 
them a genus apart because they lay different eggs. 

Dr. C. Finlay, Habana, expressed his admiration for the work of 
the commission. He believes that this session of the congress will go 
down in history as of great importance and that the differences 
between his opinion and that held by the commission will disappear 
in the course of time. He states that they were based on the fact 
that he investigated with three varieties of mosquitoes, while the 
commission has been restricted to one variety; that the board was 
placed on better footing for obtaining satisfactory results; that the 
negative result obtained by the inoculation of mosquitoes of short 
infection should not induce the commission or the board to make 
such hard and biased rules as are evidenced in its conclusions. 

Dr. Reed, in conclusion, said he was profoundly impressed with 
the interest and attention given to these experiments. In regard to 
the moral aspect of the ease, he did not think that anyone appreciated 
the position in which he found himself — the difficulties that beset 
his path. The first experiment was made on a member of the board, 
Dr. Carroll. The senior member expected to take his bite in turn, 
but was unexpectedly called north. As no animal could be given 
the disease, and it was useless to follow the previous indefinite experi- 
ments, it was absolutely necessary to make these experiments on 
human subjects, or otherwise volumes could have been written and 



YELLOW FEVER. 89 

discussed, and yet we would have been no nearer the truth than at first. 
No progress could have been made toward an exact knowledge of the 
disease unless human subjects had been used. All experiments were 
performed on persons who had given their free consent. 

In reference to the remarks of Dr. Holbeck, of Charleston, the dis- 
infection of vessels should by no means be dispensed with, but only 
of such articles as bedding and clothing, though it is necessary to get 
rid of the mosquitoes, and this simplified the process of disinfection. 

In regard to the remarks of Dr. Gutierrez, in reference to the name 
of the mosquito, Dr. Howard, of Baltimore, told him that Culex 
fasciatus is identical with Culex tiniads as described by Giles. Theo- 
bolt separates Culex tiniads from the genus Culex and places it in a 
new genus, Stegamina. These lay their eggs in a peculiar way, and 
there is also a difference in the anterior claws of the male insect from 
those of the other Culex. There is also a difference in the larva of 
the Culex fasciatus. It is very interesting also to note the fact that 
this is the very mosquito that Dr. Finlay used in his experiments 
and that this particular mosquito does not belong to the genus Culex; 
therefore malaria has a genus of its own, Anopheles, and yellow fever 
the genus Stegamina. 



Chapter 4. 

THE PROPAGATION OF YELLOW FEVER— OBSERVATIONS BASED 
ON RECENT RESEARCHES. 1 

By Walter Reed, M. D., Surgeon, United States Army. 

Mr. President and Gentlemen of the Faculty: If, upon 
receipt of your kind invitation to be present with you to-night my 
first impulse was to decline, I beg that you will not attribute this 
to any want of appreciation on my part of the honor conferred, but 
solely to my desire to avoid what I felt would be a very embarrassing 
position should I attempt to follow in the footsteps of the dis- 
tinguished gentlemen whom you have invited to fill this position 
from year to year. Recognizing in them, as all willing leaders do, 
leaders in the profession, who, by their well-considered addresses, 
have been able to add so much to the scientific interest of your 
annual meetings, I could but feel that the burden which you proposed 
to put upon me was greater than I could bear. That, nevertheless, 
I am here in the capacity of your annual speaker is due to my unwill- 
ingness even to appear disobliging to this old and honorable asso- 
ciation of physicians, among whose number I find included some 
of my most valued friends; friends who in years gone by have labored 
so faithfully to instill into my mind the value of the scientific method, 
but to whom I have been able to make such small return. If, there- 
fore, I drew some encouragement from the feeling that I should not 
be wholly among strangers, I found yet more in the thought that 
such an eminent body of physicians as this faculty must ever be 
willing to welcome any contribution that promises to shed light 
upon a subject hitherto enshrouded in darkness, and which thereby 
holds out the prospect of an addition to our knowledge in the larger 
field of preventive medicine. 

In the hope that what I. have to say to-night may contribute to 
the solution of a somewhat obscure problem, and may assist us 
hereafter in the struggle with a grave epidemic disease, I have con- 
cluded to present for your consideration "The propagation of yellow 
fever, based on recent researches." 

Before proceeding to the discussion of this subject, it is fitting that 
I should pay brief tribute to the memory of a former member of 
this faculty, the late Dr. Jesse W. Lazear, United States Army. I 
can hardly trust myself to speak of my late colleague, since the men- 
tion of his name brings back such scenes of anxiety and depression 
as one recalls only with pain. Along with these sad memories, 
however, come other recollections of a manly and fearless devotion 
to duty such as I have never seen equaled. In the discharge of 
the latter, Dr. Lazear seemed absolutely tireless and quite oblivious 

J Address delivered at the One hundred and third annual meeting of the Medical and Chirurgical Faculty 
of the State of Maryland, held at Baltimore, April 24-27, 1901. 

90 



YELLOW FEVER. 9l 

of self. Filled with an earnest enthusiasm for the advancement of 
his profession and for the cause of science, he let no opportunity 
pass unimproved. Although the evening might find him discouraged 
over the difficult problem at hand, with the morning's return he 
again took up the task full of eagerness and hope. During a service 
of less than one year in Cuba he won the good will and respect of 
his brother officers and the affection of his immediate associates. 
Almost at the beginning of what promised to be a life full of usefulness 
and good works he was suddenly stricken, and, dying, added one 
more name to that imperishable roll of honor to which none others 
belong than martyrs to the cause of humanity. 

It is my own earnest wish that, whatever credit may be hereafter 
given to the work of the American commission in Cuba during the 
past year, the name of my late colleague, Dr. Lazear, may be always 
associated therewith. 

I do not propose to set before you this evening so much the views 
of others in relation to the etiology of yellow fever, or to the conditions 
under which it originates and spreads, as to give you the results of 
my own experience with regard to the manner in which this disease 
propagates itself. In the ordinary course of Army administration, I 
found myself brought in contact with yellow fever during the sum- 
mer of 1900, under such circumstances as permitted me to give my 
entire time to the study of its etiology and propagation. Permit me 
here to remark that so many claims have been made as to the specific 
cause of yellow fever — claims that could not be confirmed by other 
investigators — that one must needs feel considerable hesitancy in 
considering this remarkable disease from any aspect. I must con- 
fess that I have experienced, in the highest degree, this feeling of 
reluctance to write or speak about yellow fever, especially when I 
recall the frame of mind of myself and my colleagues — that of utter 
perplexity and wonder — as we stood by the bedside of patients, or at 
the autopsy table of those who had died of this mysterious malady. 
I trust, therefore, that whatever I may say here to-night will be 
considered as a modest expression of opinion growing out of an 
unprejudiced study of yellow fever, for the most part from the point 
of view of its propagation. 

Although considerable attention had been given to the laboratory 
study of the microorganisms isolated by Sternberg and Sanarelli 
from the organs of yellow-fever cadavers, this did not enable one to 
form any opinion concerning the nature of the disease or the mode 
of its propagation. 

At the time of our arrival in Cuba — June, 1900 — the situation as 
regards the etiology of yellow fever may be briefly stated as follows : 
The claims of all investigators for the discovery of the specific agent 
of this disease had been disproved by the exhaustive work of Stern- 
berg, 1 published in 1890, except that made by Dr. Sanarelli, in June, 
1897, for his bacillus icteroides. I need not take up time here with 
mention of those who had investigated Sanarelli's claim, except to 
state that the confirmation of his discovery came chiefly from workers 
in the United States, of whom 1 may speak of Achinard and Woodson, 
of New Orleans, and especially of Wasdin and Geddings, of the 

1 Ileport on the Etiology and Prevention of Yellow Fever, 1890. 



92 YELLOW FEVER. 

Marine-Hospital Service. The latter, in a report x submitted during the 
summer of 1899, accepted in the fullest Sanarelli's claim for the 
specific character of bacillus icteroides, basing their confirmation on 
the rinding of this bacillus in 13 out of 14 cases of yellow fever studied 
by them in the city of Habana. Under these circumstances, it was 
of the first importance that we should give our entire time to the 
search for bacillus icteroides in the bodies of yellow-fever cases. The 
result of this study, embracing 21 cases during life and 11 autopsies, 
and which was entirely negative, has already been given in our 
Preliminary Note, 2 read at the last meeting of the American Public 
Health Association (1900). 

Turning for a moment to our knowledge concerning the mode of 
propagation of yellow fever, the situation, when we began work, was 
about as follows : The battle for or against its importation having been 
already decided in favor of the former belief, its transmissibility from 
place to place was attributed to the individual affected by the disease, 
but especially to his clothing; with the proviso, however, that 
intimately connected with its spread was involved a proper constitu- 
tion of the atmosphere of the pl,ace, this latter due chiefly to insani- 
tary conditions of soil. That the excreta of the patient contained 
the specific agent of the disease was supported by many good authori- 
ties. That the disease could be propagated by fomites was not dis- 
puted by anyone. Against its spread by the sick and by fomites all 
quarantine measures were being then directed. 

The theory of Finlay for the propagation of yellow fever by the 
mosquito, concerning which I shall presently have something to say, 
had either gained no credence or been rejected by reason of the absence 
of any results that had been presented by its author in support of it. 
In the meantime, and before we had completed our search for 
Sanarelli's bacillus, certain facts had been cropping out, as it were, 
which served to arrest the attention. Just here, wmile mentioning 
the first fact, let me say that one does not like to confess his ignorance 
of such a well-known disease as yellow fever, especially before an 
audience some of whose members may have already treated cases 
during the last epidemic in this city, in the year 1876 ; and yet candor 
compels me to record my very great surprise, when brought face to 
face with yellow fever, to learn that attendance on patients by non- 
immune nurses, in every stage of the malady, involved no danger. 
In other words, that yellow fever, both in the wards at Columbia 
Barracks, as well as in the wards of Las Animas Hospital, Habana, 
was not contracted by the attendants under circumstances such as 
those in which typhoid fever and Asiatic cholera are too often con- 
veyed. Further inquiry along this line seemed to indicate that the 
disease had not been contracted in hospitals, even during the earlier 
epidemics, when disinfection of articles of clothing and bedding was 
unknown. 

A second fact which appeared worthy of note, was the discharge of 
patients from the wards during early convalescence, and their return 
to the companionship of their comrades with apparently no danger 
of establishing fresh foci of the disease. This hardly seemed in 
keeping with the presence of a specific agent in the excreta of the sick. 

A third fact which stood out prominently was that, in certain of 
our cases, no growth whatever was obtained on our present laboratory 

i The Cause of Yellow Fever. Washington, 1899. 

2 The Etiology of Yellow Fever. A Preliminary Note. Phil. Med. Journal, Oct. 27, 1900. 



YELLOW FEVER. 93 

media, either by frequent cultures taken from the blood during life 
or from the organs after death. In other words, no bacterium was 
obtainable by aerobic methods, in certain of our cases, either during 
life or after death. This result had considerable weight in controlling 
our future work. 

During the time that these cases were being studied, opportunity 
was afforded to investigate an epidemic of fever which was prevailing 
in Pinar del Rio Barracks, near the town of this name, distant 110 
miles from Habana, and of which fever several soldiers, in a garrison 
of about 900 men, had already died. A visit was made to this garrison 
with my colleague, Dr. Agramonte, on the 31st day of July, 1900, 
and a body sectioned the same afternoon. The lesions found were 
those of yellow fever. Inquiry showed that under the diagnosis of 
" remittent malarial fever" or "pernicious malarial fever," the disease 
had been prevailing for at least 37 days prior to our arrival — July 21 — 
and that about 35 cases had been under treatment in the post hospital, 
of which number 11 had died. As the true nature of the disease had 
not been suspected, no precautionary measures had been taken as 
regards the disinfection of bedding and clothing used by the patients, 
except that in case of death the sheets and pillow slips were put in 
bichloride solution and the mattresses and pillow exposed to sun- 
light. An order required that the excreta of all patients under treat- 
ment in this hospital should be carefully disinfected, and this was 
probably carried out fairly well. The excreta for the garrison at large 
were incinerated in permanent crematories, fires being lighted in 
these twice a week. 

Notwithstanding the omission to disinfect the bulk of the contami- 
nated articles of bedding and clothing, the disease had not been 
contracted by the nurses, nor by the other patients in the several 
wards, nor by the three men who washed all of these articles. A 
little inquiry showed that contaminated clothing was in all of the 
eight barrack rooms without apparent detriment to the occupants. 
Further investigation showed that a death from yellow fever had 
occurred in this garrison as early as May 16, 1900, and that the source 
of infection for this case, as well as for the present outbreak, was in the 
immediately adjacent town of Pinar del Rio, to which the soldiers 
had free access. 

An interesting observation Avas the sudden attack of yellow fever 
experienced on July 12, 1900, by a general prisoner who had been 
confined in a cell in the guardhouse since June 6, 1900. His death 
occurred at the post hospital on July 18, 1900. This cell was occupied 
at the time by eight other prisoners, none of whom contracted the 
disease, although one of them continued to occupy the bunk vacated 
by the sick man. As these nine prisoners had been kept under strict 
military guard, it was impossible that the individual attacked could 
have acquired his infection in the town of Pinar del Rio. He was, as 
far as could be ascertained, exposed to no source of infection to which 
his companions had not been equally exposed, and yet he alone 
acquired the disease. It was conjectured at the time that perhaps 
some insect capable of conveying the infection, such as the mosquito, 
had entered through the cell window, bitten this particular prisoner, 
and then passed out. This was, however, only a supposition. 

Two instances of undoubted exposure to fomites, involving four 
individuals, came under my observation during this inspection. In 



94 YELLOW FEVER. 

the one case a box of clothing, belonging to a soldier who had died of 
yellow fever on July 3, and which had been packed by an enlisted 
man on July 4, and placed in the company storeroom, was un- 
packed for the purpose of making an inventory of the articles, and 
carefully repacked on July 18 by two nonimmune soldiers, who did 
not contract the disease by this exposure. In the other case the 
very bed vacated on July 18 by the commissary sergeant, who was 
taken sick on July 17, and died on July 21, was occupied by a 
nonimmune soldier on the nights of the 19th and 20th of July. 
Although this individual was badly frightened when the true character 
of the sergeant's attack was announced, the combination of fright 
and exposure to fomites was not sufficient to produce an attack of 
yellow fever. 

The data gathered, therefore, during the investigation of this small 
epidemic at Pinar del Rio did not tend to strengthen one's belief in 
the theory of the propagation of yellow fever by fomites. This belief 
had already been shaken by the manner in which the disease had 
spread in the town of Quemados, Cuba, from which we had obtained 
cases for bacteriologic study; for here we saw the disease pass from 
No. 102 Real Street around the corner to No. 20 General Lee Street, 
and thence to a house immediately across this latter street, without 
the passage of any persons between these three houses, and to the 
exclusion of any article of clothing, as the three families had no 
acquaintance whatever with each other. Here the infection was 
just as plainly carried through the air as it had been taken, through 
this medium, to the prisoner in the cell at Pinar del Rio. We also 
observed in this town that the contagion passed down General Lee 
Street with a bound to the distance of a square, passing in its journey 
a house containing two nonimmunes, only to return a few days later 
to this very house and seize upon both of its nonimmune inmates. 
This hardly seemed in keeping with the idea of a diffusible poison 
carried by the atmosphere. During our first week on the island, 
we noted in a house in Quemados, where the husband and wife were 
taken down with yellow fever a few days apart, that neither the 
young daughter, who was removed to a place of safety on the fourth 
day, nor an attendant who had remained in the sick room for the 
entire 24 hours of the seventh day, had acquired the disease; but 
that of the two remaining nurses who continued to perform their 
duties, one was seized on the fourteenth day and the other on the 
fifteenth day with an attack of yellow fever. This observation was 
recorded at the time for what it was worth. Later it was found to 
harmonize with the observations which had been made by Surg. 
Henry R. Carter, of the Marine-Hospital Service, in 1898. As I shall 
recur to these observations later in my remarks, it will suffice to here 
state that at this stage of our investigation it seemed to me, and I 
so expressed the opinion to my colleagues, that the time had arrived 
when the plan of our work should be radically changed; that the 
search for the specific agent of yellow fever, while not abandoned, 
should be given secondary consideration, until we had first^ definitely 
learned something about the way or ways in which the disease was 
propagated from the sick to the well. I felt well-nigh convinced 
that we could obtain no light whatever upon the task that had been 
set before us, unless we substituted this fine of work for the one we 
had been pursuing, and that in view of the splendid work of Ross, 



YELLOW FEVER. 95 

Bignami, and others with regard to the propagation of malarial fever, 
together with the well-known thermal influences intimately con- 
nected not only with the epidemiology of the disease in the United 
States, but also with its endemiology on the Island of Cuba, it was 
of the highest importance that the agency of an intermediate host, 
such as the mosquito, should either be proven or disproven. 

Remember, if you please, that here we were dealing with an epi- 
demic disease concerning which there was no evidence whatever to 
show that it had ever been spread by contamination of either water 
or food; that it had always demanded a certain elevated tempera- 
ture before it would begin its progress, which latter, both in its man- 
ner and rate, was quite unlike that of other epidemic diseases, such 
as smallpox or typhoid fever or Asiatic cholera; that once having 
begun its march, no Irvgienic measures ever instituted had been able 
to arrest its course, except depopulation of the locality affected; 
that while, if introduced into certain localities, it would readily propa- 
gate itself, those sick with this disease could be carried in large num- 
bers into other places without any danger of its spread — a fact which 
had been attested in hundreds of instances; that ships with nonim- 
mune crews could remain at anchor with perfect safety at about 300 
yards from an infected shore. Couple with this the natural law by 
which it was governed, viz, its prompt control by frost, and tell me 
what other epidemic disease could be associated in the mind with 
this except malarial fever. 

The theory that the spread of yellow fever could not be explained 
by the assumption of a diffusible miasm in the atmosphere, but 
required the presence of an intermediate host, appears to have been 
first advanced by Dr. J. C. Nott, of Mobile, Ala., in March, 1848. 
His views were given in full in the New Orleans Medical Journal for 
that year. It was also in this paper that Nott suggested the mos- 
quito as the possible agent in the dissemination of malarial fevers. 
He evidently did not have in mind the mosquito as the bearer of the 
yellow-fever poison, but rather that this important office was per- 
formed by some insect or insects that remained very close to the 
ground. Referring to the fact to which all writers were agreed, that 
a very imperfect barrier, such as a row of houses or of trees, would 
often protect dwellings from the access of malarial poison, he says: 

I have been able in my researches to discover no facts of this kind in connection 
with yellow fever, and my personal observation repudiates this in toto. We neyer 
find yellow fever, as the sportsman says, "up a tree," but on the contrary the materies 
morbi, whatever it may be, creeps along the ground, regardless of winds, passing 
under and through houses and trees, etc., and knowing no impediment but a sheet 
of water. 

Again : 

It is a curious fact that from 1829 to 1837 there was no epidemic of yellow fever in 
Mobile, and during this time the streets were beautifully shelled; since 1837 we have 
had it five times and the shelling was not continued. If the insect theory be correct, 
could the lime be an impediment to their progress across the street? 

To Dr. Carlos J. Finlay, of Habana, must be given, however, full 
credit for the theory of the propagation of yellow fever by means of 
the mosquito, which he proposed in a paper read before the Royal 
Academy in that city at its session on the 14th day of August, 1881. 
From that date to the present time Finlay has made a number of 
valuable contributions to the origin and mode of transmission and 



96 YELLOW FEVEK. 

the prevention of yellow fever. During this time his views have 
undergone some slight modification. Starting with the idea that the 
specific poison adhered to the mosquito's proboscis and was thus 
mechanically transferred to the individual next bitten (which specific 
agent was claimed by him in 1887, and even at the present time, to be 
his micrococcus tetragenus febris jflavse), he later — 1899 — modified 
his original theory, based upon the studies of Theobald Smith on 
Texas fever, "so as to include the important circumstances that the 
faculty of transmitting the yellow-fever ' germ need not be limited 
to the parent insect, directly contaminated by stinging a yellow-fever 
patient (or perhaps by contact with or feeding from his discharges), 
but may be likewise inherited by the next generation of mosquitoes 
issued from the contaminated parent" (New York Medical Record, 
May 27, 1900). Of the 100 individuals experimented upon from 
June, 1881, to May, 1895, Finlay claimed to have produced three 
cases of "mild albuminuric fever" after a period of incubation 
varying from 5 to 25 days; but as he exercised no control over these 
individuals, to the exclusion of other sources of infection, no value 
could be attached to his results. If, indeed, one were guided by the 
results obtained, the only logical conclusion to be drawn was that 
Finlay had disproved his own theory. His failure to produce posi- 
tive results — which we now believe to be due to the fact that he did 
not keep his insects for a sufficient length of time after contamination 
before applying them to the individual to be infected — doubtless led 
Finlay to promulgate the later idea that the bite of the contaminated 
mosquito, while not producing the disease, conferred immunity upon 
the individual bitten. He has made use of the bite of the contami- 
nated mosquito for this purpose in a considerable number of indi- 
viduals. Notwithstanding the fact that Finlay had no results to 
show in support of his theory, and that the latter had been wholly 
rejected by other investigators, the argument in favor of an inter- 
mediate host seemed so strong, as I have already stated, that further 
investigation along this line was determined upon. The mosquito 
selected was the one that had been used by Finlay in his previous 
work, and which, with Culex pungens, is the most prevalent and 
annoying mosquito in the city of Habana, and for that matter in all 
the larger towns on the island. Originally designated by Fabricius 
as Culex fasciatus, 1 it had later been called by Desvoidy, Culex 
mosquito. Unlike Culex pungens this mosquito bites by day as well 
as during the nighttime. Judging from my own experience, I should 
say that its favorite hours for feeding were from 4 p. m. to 10 p. m. 

In our preliminary note, above referred to, we recorded, among 11 
individuals bitten by contaminated mosquitoes of this species, 9 
negative and 2 positive results; the attack in both of the latter 
occurring within the period of incubation of yellow fever. As the 
circumstances surrounding the infection of one of these cases was 
such as to exclude any other source of infection, we announced the 
conclusion that "the mosquito served as the intermediate host for 
the parasite of yellow fever." Subsequent observations have pointed, 
in the most convincing manner, to the soundness of this conclusion. 
It is to these later observations that I now desire to invite your 
attention. 



i It is interesting and important to observe that since the publication of cur Preliminary Note, Theobold, 
the English entomologist, has taken C. fasciatus from the genus Culex and placed it in a new genus— 
Stegomyia. 



YELLOW FEVER. 97 

Dismiss from, your minds, if you please, the idea that yellow fever 
is so prevalent on the island of Cuba, and that the ways of acquiring 
the disease are so numerous, that experimental results obtained at 
any point in the so-called endemic zone of yellow fever must be 
thereby vitiated. Nothing to my mind could be more improbable 
than such an opinion; for, as a matter of fact, yellow fever has been 
confined, during the year 1900, to Habana and a few other towns, 
coast or inland, and has not been present elsewhere on the island. 
Hence any location selected, provided it should be 1 mile from such 
a center of infection and surrounded by proper safeguards, would be 
just as free from the occurrence of yellow fever as if it were located 
10 miles from such a town. My own experience on the island of 
Cuba had already taught me that yellow fever could be easily kept 
out of a military garrison, although prevailing in epidemic form in a 
town less than 1 mile distant. For this reason it was not considered 
advisable to establish our experimental sanitary station at a greater 
distance than 1 mile from Quemados, Cuba. Thus Camp Lazear 
could be easily reached by the members of the board and was con- 
veniently located as regards its base of supplies. The occurrences at 
this camp fully justified this decision. Placed in an open field, 
which was fairly swept at all times by the prevalent winds, and having 
a military garrison each of whose members had been personally 
selected by reason of former good conduct and interest in the work 
to be here undertaken, no difficulty whatever was experienced in 
maintaining the strictest quarantine against the outside. 

Let us now present to you, as succinctly as possible, our observa- 
tions at this camp, prefacing what I shall have to say with the 
remark that here we proposed to attempt the infection of nonimmune 
individuals in three ways, viz, first, by the bites of mosquitoes that 
had previously bitten cases of yellow fever; secondly, by the injec- 
tion of blood taken during the early stages from the general circula- 
tion of those suffering with the disease; and, thirdly, by exposure to 
the most intimate contact with fo mites. For this purpose, in addition 
to the seven tents provided for the quartering of the detachment, 
two frame buildings, each 14 by 20 feet in size, were constructed. 
These buildings, having a cubic capacity of 2,800 feet, were exactly 
similar, except that one of them, known as the "Infected mosquito 
building," was divided near its middle by a permanent wire-screen 
partition and had good ventilation; while the other, designated as 
the "Infected clothing building," was purposely so constructed as 
to exclude anything like efficient ventilation. These houses were 
placed on opposite sides of a small valley, about 80 yards apart, and 
each 75 yards distant from the camp proper. Both houses were 
provided with wire-screen windows and double wire-screen doors, so 
that mosquitoes could be kept without or within the buildings, as 
the experimenter might desire. 

At first the results obtained at this station were not encouraging. 
From November 20, 1900, the date of the establishment of the sta- 
tion, until December 4 — a period of 2 weeks — we had tried to infect 
4 individuals, with entirely negative results. Two of these had been 
bitten twice, at intervals of 3 days, by contaminated mosquitoes 
which had been kept from 10 to 14 days after they had fed on yellow- 
fever cases ; while the other 2 nonimmunes had been thrice bitten, at 
79965°— S. Doc. 822, 61-3 7 



98 YELLOW FEVER. 

the same intervals, by mosquitoes that had bitten cases of yellow 
fever 10 to 18 days before. As the weather during this time was cool 
and the insects had been kept at room temperature (and this is prac- 
tically outdoor temperature in Cuba), we conjectured that the nega- 
tive results might, perhaps, be thus explained. We remembered that 
Daniels 1 in repeating, during the winter season, Ross's observations 
with proteosoma infection of birds, had obtained a much smaller per- 
centage of successes than had Ross, who worked during summer 
weather. We would have been glad to draw some encouragement 
from our negative experiments, also, with infected bedding, but, as 
at this date (Dec. 4) our 3 subjects had been sleeping with fo mites 
only 4 nights (which is within the period of incubation of the disease), 
this comfort was debarred. 

On the fifteenth day of our encampment therefore (Dec. 5, at 2 
p. m.) we concentrated our insects, so to speak, on one of these non- 
immunes — Kissinger by name — selecting 5 of our most promising 
mosquitoes for the purpose. These had been contaminated as fol- 
follows: Two, 15 days; 1, 19 days; and 2, 21 days previously. This 
inoculation was more successful, for, at the expiration of 3 days and 
9^ hours the subject, who had been under strict quarantine during 
15 days, was suddenly seized with a chill about midnight, December 8, 
which was the beginning of a well-marked attack of yellow fever. 

I can not let this opportunity pass without expressing my admi- 
ration of the conduct of this young Ohio soldier, who volunteered for 
this experiment, as he expressed it, "solely in the interest of humanity 
and the cause of science," and with the only proviso that he should 
receive no pecuniary reward. In my opinion this exhibition of 
moral courage has never been surpassed in the annals of the Army of 
the United States. 

The following morning (Sunday, Dec. 9, at 10.30 a. m.) we 
selected from those insects that had bitten Case I, one mosquito that 
seemed to us to possess the best record of contamination, as it had 
bitten a fatal case of yellow fever, on the second day of the disease, 
19 days before. This insect was applied to a Spanish immigrant, 
who had been strictly quarantined at our station for 19 days. At the 
expiration of 3 days and 11 hours (Dec. 9, 9.30 p. m.) this individual 
was also seized with an attack of yellow fever. 

In the meanwhile, on December 8, 1900, at 4 o'clock p. m., we had 
applied to a young Spaniard three of the mosquitoes that had, three 
days previously, bitten Case I, together with an additional mosquito 
contaminated 17 days before. At the end of 4 days and 20 hours 
(Dec. 13, noon) this "Spaniard suddenly lost his vivacity and took to 
his bed. The following morning at 9 a. m. his febrile paroxysm 
began. His case, which was the mildest of our series, was also marked 
by a long period of incubation, viz, 5 days and 17 hours. He had 
been in quarantine 9 days. 

December 11, at 4.30 p. m., the identical 4 insects which had bitten 
Case III were fed on a Spanish immigrant who had been in quarantine 
for the past 21 days. At the expiration of 3 days and 19J hours 
(Dec. 15, noon) he was likewise seized with yellow fever. 

Thus within the period of one week — December 9 to 15 — we had 
succeeded in producing an attack of yellow fever in each of the 4 

x On transmission of Proteosoma to Birds by the Mosquito— Royal Society, Reports of Malarial Com- 
mittee. London, 1900. 



YELLOW FEVER. 99 

individuals whom we had caused contaminated insects to bite, and 
in all save 1 of the 5 nonimmunes whom we had originally selected 
for experimentation. 

It can readily be imagined that the concurrence of 4 cases of yellow 
fever in our small command of 12 nonimmunes within the space of 
1 week, while giving rise to feelings of exultation in the hearts of the 
experimenters, in view of the vast importance attaching to these re- 
sults, might inspire quite other sentiments in the bosoms of those 
who had previously consented to submit themselves to the mos- 
quito's bite. In fact, several of our good-natured Spanish friends 
who had jokingly compared our mosquitoes to "the little flies that 
buzzed harmlessly about their tables," suddenly appeared to lose all 
interest in the progress of science, and, forgetting for the moment 
even their own personal aggrandizement, incontinently severed their 
connection with Camp Lazear. Personally, while lamenting to some 
extent their departure, I could not but feel that in placing them- 
selves beyond our control they were exercising the soundest judgment. 
In striking contrast to the want of confidence shown by these Anda- 
lusians who had agreed to be bitten by mosquitoes was the conduct 
now displayed by the three young Americans, who had consented to 
jeopardize their lives by exposure to fomites and who, as a matter of 
fact, had already spent 15 nights in a small, illy ventilated building, 
breathing in an atmosphere dreadfully contaminated by the soiled 
garments of yellow-fever patients. With the occurrence of these 
cases of mosquito infection, the countenances of these men, which had 
before borne the serious aspect of those who were bravely facing an 
unseen foe, suddenly took on the glad expression of "schoolboys let 
out for a holiday," and from this time their contempt for "fomites" 
could not find sufficient expression. Thus illustrating once more, 
gentlemen, the old adage that familiarity, even with fomites, may 
breed contempt. 

As the continued good health of those who were occupying the 
''infected clothing building" pointed strongly to the harmlessness 
of fomites, the next experiment at this station was undertaken for the 
purpose of demonstrating that the essential factor in the infection of 
a building with } r ellow fever is the presence therein of mosquitoes that 
have bitten cases of yellow fever. 

Accordingly at 11.55 a. m., December 21, 1900, 15 mosquitoes were 
freed in the larger room of the "infected mosquito building," which, 
as I have said, was divided into two compartments by a wire-screen 
partition. The interval that had elapsed since the contamination 
of these insects was as follows: One, 24 days; three, 12 days; four, 
8 days; and seven, 5 days. The only articles of furniture in this 
building consisted of three beds, one being placed in the mosquito 
room and two beyond the wire screen, these latter intended to be 
occupied by two "control" nonimmunes. The articles of bedding 
as well as the bedsteads had been carefully disinfected with steam. 
At noon on the same day, 5 minutes after the mosquitoes had been 
placed therein, a plucky Ohio boy, Moran by name, clad only in his 
nightshirt, and fresh from a bath, entered the room containing the 
mosquitoes, where he lay down for a period of 30 minutes. On the 
opposite of the screen were the two "controls" and one other non- 
immune. Within 2 minutes from Moran's entrance he was being 
bitten about the face and hands by the insects that had promptly 



100 YELLOW FEVER. 

settled down upon him. Seven in all bit him at this visit. At 4.30 
p. m., the same day, he again entered and remained 20 minutes, 
during which time 5 others bit him. The following day at 4.30 p. m., 
he again entered and remained 15 minutes, during which time 3 
insects bit him, making the number 15 that had fed at these three 
visits. The building was then closed, except that the two non- 
immune ' ' controls ' ' continued to occupy the beds on the noninf ected 
side of the screen. On Christmas morning, at 11 a. m., this brave 
lad was stricken with yellow fever, and had a sharp attack, which 
he bore without a murmur. The period of incubation in this 
case was 3 days and 23 hours, counting from his first visit, or 2 
days and 17^ hours if reckoned from his last visit. The two 
" controls" who had slept each night in this house, only protected 
by the wire screen, but breathing the common atmosphere of the 
building, had remained in good health. They continued to so remain, 
although required to sleep here for 13 additional nights. As Moran 
had remained in strict quarantine for the period of 32 days prior to 
his attack, the source of his infection must be found within this 
house. 

In the order of succession, the next experiment undertaken at this 
camp was the injection of blood, taken from Case V (Moran), beneath 
the skin of a Spaniard, but I will defer further mention of this line of 
experimentation until I have completed the mosquito series, as these 
are by far the most important. I, therefore, invite your attention 
to Case VI, Martinez by name. His case is of interest as bearing 
upon the number of days which must elapse after the contamination 
of the mosquito before it can convey the disease to a second indi- 
vidual. 

An additional point of some importance, I think, is that whereas 
prior to the time of Moran' s infection (Case V) the contaminated 
mosquitoes had been taken to the men in their tents and there applied, 
from this date — December 17 — the subjects were invited to visit a 
particular room attached to our " Mosquito building," but quite 
separate from it, where the contaminated insects were kept at sum- 
mer temperature, and were there given the opportunity of exposing 
themselves to an attack of yellow fever by putting their hands inside 
of certain mosquito-inhabited jars. I may as well tell you now that 
of seven persons who availed themselves of this privilege five 
acquired yellow fever. 

After a quarantine period, therefore, of 9 days, Martinez visited 
this room on December 17, 1900, and was bitten by 14 mosquitoes 
which 4 days before had fed upon Case I of this series. The result 
was quite negative. December 24, or on the eleventh day after 
contamination, the subject was again bitten by 7 of these insects — 
all that remained of the original 14. Again no infection took place. 
After 6 full days, or on December 30, at 11 a. m., Martinez was again 
bitten by the surviving 4 of these mosquitoes, i. e., on the seven- 
teenth day after their contamination. On the fourth day thereafter, 
January 3, 1901, at 10.30 a. m., he was seized with yellow fever, 
which ran a typical course. The period of incubation was 3 days 
22J hours. Although we can not say on what particular day these 
insects became capable of conveying the disease, we are able to state 
that they were incapable of infecting on the fourth or eleventh day 



YELLOW FEVER. 101 

after contamination. This experiment agrees with others that we 
have made during this investigation and in which we have failed to 
convey the disease by the bites of insects at intervals varying from 
2 to 9 days after contamination. These observations seem to indi- 
cate that after the parasite has been taken into the mosquito's stom- 
ach a certain number of days must elapse before the insect is capable 
of reconveying it to a second individual. This period probably rep- 
resents the time required for the parasite to undergo its cycle of devel- 
opment and reach the mosquito's salivary glands, and, as far as our 
experience goes, would appear to be about 12 days in summer weather 
and most probably about 18 or more days during the cooler winter 
months. Case VI, therefore, does not support the opinion of Finlay 
that the bite of the contaminated mosquito confers immunity against 
a subsequent attack of the disease, since we have seen that neither 
the bites of 14 insects on the fourth day nor the bites of 7 on the elev- 
enth day after contamination prevented in the least the conveyance 
of the infection by the bites of 4 only of these mosquitoes on the seven- 
teenth day. 

I will now ask you to look at Case IX, as this case serves to illus- 
trate some points of interest. In the first place, this subject, an 
American, was bitten by insects that had fed upon Case I of our series 
on the third day of his illness ; that is, during the secondary fever which 
followed a complete intermission in this case. Secondly, these mos- 
quitoes had been kept alive on sugar and water for a period of 39 days 
before being applied to Case IX. Of the original 5 insects that had 
bitten Case I on the third day, 4 were still alive on the thirty-ninth day 
thereafter and 3 showed every evidence of good appetite. Thirdly, 
this particular subject having passed 21 nights in the "Infected clo til- 
ing building," during which time he was exposed to the most intimate 
contact with fomites, without apparent detriment to his health, had 
been kept in strict quarantine for yet 30 days longer at Camp Lazear. 
At the expiration of this time, or on January 19, 1901, at 4.30 p. m., he 
visited our mosquito room, where he was bitten by these 39-day-old 
insects, 3 in number. This inoculation was followed by an attack of 
yellow fever of moderate severity, which began at 4 p. m., January 
23, the period of incubation being 3 days 23^ hours. 

Case XII you will find of equal interest, as this individual was in- 
fected, in the same room, by the bites of two of these same mosquitoes 
on the fifty-first day after their contamination, the period of incuba- 
tion being 3 days 2 J hours and the character of the attack mild, 
while Case XIII will conclusively demonstrate that these identical 
insects, on the fifty-seventh day after their contamination, were not 
only capable of conveying the infection, but of producing an attack of 
such severity that the subject's life hung in the balance for several 
days. I regret to have to state that the individual who had con- 
sented to be bitten by these insects on the sixty-fifth day after their 
contamination failed to fulfill his promise at the last moment; so 
that otherwise I can not say to what old age these mosquitoes might 
have attained. Deprived of further opportunity to feed on human 
blood, one died on the sixty-ninth day and the other on the seventy- 
first day after their original contamination. The duration of life in 
the case of these mosquitoes will readily explain how the poison of 
yellow 7 fever can remain even in a depopulated area for a period of 



102 YELLOW FEVER. 

2^ months; so that, as is well known, those who enter the infected 
area, even at the expiration of this period, are liable to acquire the 
disease. 

Case XIV is that of our tenth and last successful mosquito infec- 
tion at Camp Lazear. Tins individual after 25 days' quarantine, 
having been bitten on February 7, 1901, at 2 p. m., by two mosqui- 
toes on the sixteenth day after their contamination, was seized with 
an attack of yellow fever at noon, February 10, after an incubation 
stage of 2 days 22 hours. 

Thus you will observe that at tins station, under strict quarantine 
precautions, we succeeded in conveying the disease to 10 nonimmunes 
by means of the bites of mosquitoes that had previously fed on cases 
of yellow fever at intervals varying from 16 to 57 days before being 
applied to the person to be infected; that the attack of yellow fever 
always followed the bite of the mosquito within the period of incuba- 
tion of this disease, and that during the period which elapsed from 
December 5, 1900, the date of our first inoculation, till February 7, 
1901, the date of our last inoculation (65 days), the order of occur- 
rence of these cases corresponds with the order of inoculation, except 
that Case II, having a longer incubation period than Case III, the 
order of their relative occurrence became reversed. 

Table I serves to illustrate this point. 

By an examination of tins table it will be seen that of 13 individuals 
whom we attempted to infect by bites of contaminated mosquitoes 
we succeeded in 10, or 76.92 per cent. Of the three negative cases, it 
will be observed that one (Case VI), who had reacted negatively to 
the subcutaneous injection of 1.5 c. c. of blood on December 26, 1900, 
also reacted negatively to the bites of mosquitoes on January 8, 1901, 
and this notwithstanding the fact that he was bitten by the very same 
insects which nine days before had infected Case VII. We have good 
ground for the opinion, therefore, that this Spaniard may be looked 
upon as one who possessed a natural immunity to yellow fever, espe- 
cially as he was the only one of five persons who did not develop the 
disease after receiving an injection of blood taken from the general 
circulation, and was also the only one of five nonimmunes who did 
not contract yellow fever when bitten by insects winch already had 
been proven capable of conveying the disease to other individuals. 
Case VIII, while negative to mosquito inoculation on December 28 
and 29, 1900, reacted positively to a blood injection (2 c. c.) on Janu- 
ary 8, 1901. This particular individual, Jernigan, entered our 
"infected mosquito building" on December 28 and 29, 1900, one 
week after Moran's visit, and was bitten on each occasion by one 
mosquito. As 66 per cent of the mosquitoes freed in the building on 
December 21, 1900, had already been destroyed — most probably by 
the small red ants that were present in considerable numbers — the 
subject may have been bitten by insects that were not more than 13 
days old, in which case he would hardly have become infected. While 
considering the advisability of adding other contaminated insects to 
those in the house for the purpose of infecting Jernigan, opportunitv 
presented for making a blood injection, and, as he was the only avail- 
able subject in the camp at the time, it was determined to make use 
of him for this purpose. 

Case XIII, our third negative case of mosquito inoculation, was 
bitten by 12 mosquitoes that had fed on Case VII within 8 hours of 



YELLOW FEVER. 103 

the commencement of his attack. Although these insects were 22 
days old when applied to Case XIII, on January 25, 1901, no result 
followed the bites. As the subcutaneous injection of 2 c. c. of blood 
taken from the general circulation of Case VII, at the end of 24 hours, 
produced an attack of yellow fever in Case VIII within the period of 
incubation, it would appear to indicate that the mosquito at certain 
periods of the disease may fail to obtain the parasite owing to its 
absence, at that particular time, from the capillary circulation. This 
is not unlike what we sometimes find as the result of an examination 
of the blood of malarial fever, especially in the sestivo-autumnal type 
of the disease. Table I also shows that, in addition to the positive 
case (VIII) to which I have already invited your attention, we 
obtained three other positive results by the subcutaneous injection 
of blood taken from the general circulation on the first and second 
days of the disease, viz, Cases VIII, XI, XII. The quantity of blood 
injected in these three cases was 1.5 c. c, 0.5 c. c, and 1 c. c, respec- 
tively. The production of yellow fever in tins way is of much scientific 
interest — first, as serving to confirm what the mosquito inoculations 
had already shown, viz, that the parasite is present in the general cir- 
culation; second, that passage through the body of the mosquito, 
although this would seem to be nature's method, is not absolutely 
essential in the life history of this microorganism; and third, that the 
period of incubation of the disease, when thus produced, corresponds 
fairly closely to that occasioned by the mosquito's bite. A point of 
considerable importance brought out by the blood injection was the 
absence from this blood, on careful bacteriologic culture, of any bac- 
terium which grows on our ordinary media by aerobic methods, thus 
excluding absolutely the bacillus icteroides of Sanarelli from further 
claim as the specific agent of yellow fever. 



104 



YELLOW FEVER. 



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YELLOW FEVER. 105 

You will recall that we undertook at Camo Lazear still a third 
method of propagating this disease, viz, by fomites. I must now tell 
you that during the whole time that we were producing cases of 
yellow fever by the bite of the mosquito and by blood injection, we 
were leaving no stone unturned in order to produce the disease by 
contact with fomites. Sleeping every night in the "Infected cloth- 
ing building," to which no sunlight ever came, and in which the 
circulation of air was purposely made as defective as possible; en- 
gaged in the morning in packing boxes with garments much soiled 
by contact with the bodies and excreta of yellow-fever patients, and 
at night unpacking these same boxes in order to obtain articles for 
their beds and clothing for their bodies — in other words, sleeping in 
the very beds and garments just vacated by cases of yellow fever, 
seven nonimmune young Americans, averaging each 21 nights amid 
such uninviting surroundings, came out of this pesthouse, so to speak, 
at the expiration of their term none the worse for their experience. 
Not one had contracted the disease. 

In the light of these results we can hardly be expected hereafter to 
lend much credence to such observations as that given by Harvey 
Brown, in 1872, x as narrated by Dr. A. A. Baldwin, of Jacksonville, 
Fla., presumbly from memory, some 13 years after the event. In 
this instance two children in Jacksonville, Fla., "contracted the 
disease by being present at the opening of a trunk belonging to their 
uncle who, a few days before leaving Habana, had visited the yellow- 
fever hospital, where he passed by the beds of those who were throw- 
ing up black vomit; and this, notwithstanding the fact that his coat, 
the only woolen clothing he had on at the time, had been sponged 
with alcohol after his return from the hospital! " 

Or this, recorded by Rochester, 2 as an example "of the wonderful 
tenacity with which fomites hold the pestiferous material" and after- 
wards "convey it to mankind with intense effect." "In September, 
1856, an infected ship from Cuba was detained at the quarantine 
anchorage off Staten Island, N. Y. Several passengers died, and 
some were ill on board. The garments and bedding were thrown 
overboard. Bay Ridge, a delightful suburban neighborhood of 
Brooklyn, lies directly across the bay, distant about 1 mile from the 
anchorage mentioned. The wind and tide deposited a number of 
garments that had been thrown away on the beach which terminated 
the lawn of Col. Charles Prince, an old and respected resident. In 
taking his usual morning walk he discovered the clothing and ex- 
amined it with his cane, not otherwise handling it. He had no sus- 
picion that it came from quarantine and never saw it again. In four 
days he was taken illl and died in a week of yellow fever." We lose 
our faith in this brine-soaked bedding when we find, according to 
Elisha Harris's report, 3 that on the Long Island shore, directly oppo- 
site the quarantine grounds (Bay Ridge) 6 cases of yellow fever and 3 
deaths from black vomit had already occurred between the 13th and 
21st of July, 1856, and that "from the latter date the malady ex- 
tended fearfully until it had visited nearly every dwelling on the 
shore of that beautiful Bay Ridge, 30 cases and 15 deaths having 
occurred in that district previous to August 1." 

1 Report on Quarantine, 1872, pp. 34 and 35. 

2 Transactions Am. Med. Association, vol. 30, 1899, pp. 128, 129. 
s Annual Report of the Physicians of Marine Hospital, 1857. 



106 YELLOW FEVER. 

I could quote many other instances contained in the literature, but 
as not one of them, as far as my search has gone, will bear the slightest 
intelligent criticism, I will not further trespass on your time except to 
say that, in my opinion, every epidemic of yellow fever that has occurred 
in the United States, both prior to and since the period when disinfec- 
tants were used, has pointed in the plainest manner to the innocence of 
fomites as a means of propagation of this disease; for with the onset of 
cold weather and under those conditions of lessened ventilation of dwell- 
ings and artificial heat that should have aided in the spread of the 
epidemic, just the contrary effect has always resulted. Under the cir- 
cumstances one must either conclude that an external temperature 
of 32° F. is quite sufficient to bring about, and that speedily, the 
thorough disinfection of the many tons of infected clothing and bed- 
ding contained in the houses of a large city at the end of an epidemic 
of yellow fever or that fomites have no part in the propagation of the 
disease. The latter conclusion, it seems to me, is the only intelligible 
one, in view of our present knowledge of the disinfectant action of 
cold on bacteria. 

Let us now see if there are any facts observed by others in connec- 
tion with the ordinary propagation of yellow fever which support 
those recorded by us as the result of mosquito bites at Camp Lazear. 
Since in our limited experience, affecting 23 individuals, we nave not 
observed the production of the disease by the bite of the mosquito 
within less than 12 days after contamination, we would expect that, 
when a case of yellow fever was imported into a town or house where 
the conditions were favorable for its propagation, a secondary case 
would not occur within a less period of time than about 14 or more 
days. I may say that various observers have noted that after the 
occurrence of the first case in a town, a considerable interval elapses 
(2 or 3 weeks) prior to the appearance of other cases. Although such 
general statements are of value, what we need are exact observa- 
tions recorded under such conditions that the secondary cases can be 
positively referred to a certain limited source of infection. This, of 
course, can best be done where the disease has been imported into 
small settlements or into isolated houses, and it was under just such 
favorable circumstances that Carter, of the Marine Hospital Service, 
made his observations at Orwood and Taylor, Miss., in 1898, "on the 
interval between the infecting and secondary cases of yellow fever." 
Here, in a community of more than average intelligence, consisting 
"not of a town, or even a hamlet, but only of a neighborhood/ ' as 
Carter puts it, it was possible to record with accuracy the date of 
introduction of the infecting cases and the date of occurrence of 
secondary cases. 

Table II gives the results of this investigation. 

This table shows that of 16 houses in which the interval between 
the infecting case and the first secondary case was recorded, 15, or 
93.7 per cent, correspond with the mosquito interval; that is, the 
secondary cases occur at just tho interval — 13 to 23 days — when we 
would expect them to develop, provided the mosquito was concerned 
in the propagation of the disease. It will be observed that in only 1 
of the 16 first secondary cases was the interval as short as 11 days 
and 15 hours. If the commencement of the attack in this case has 
been recorded correctly, it would indicate that the number of days 



YELLOW FEVER. 



107 



which we have given as " about 12 " for the development of the para- 
site within the mosquito would have to be shortened somewhat — 
probably to 10 days. In our first successful experimental case, where 
the disease was produced by the bite of the mosquito on the twelfth 
day after the insect's contamination, we could not say, of course, that 
this particular mosquito would not have conveyed the infection had 
it been allowed to bite on the tenth or eleventh day after contamina- 
tion. 

On the other hand, if we take all the secondary cases that occurred 
in these 16 houses, we will find that of a total of 71 cases, only 1 
developed the disease after so short an interval as 11 days and 15 
hours; in other words, 70, or 98.5 per cent, of the secondary cases 
occurred after an interval of 13 days. As a matter of fact only 2 of 
these secondary cases occurred within a less period than 14 days, 1 
developing on the twelfth and the other on the thirteenth day. 

Table II. — Interval between infecting and secondary cases of yellow fever. 



House. 



Year. 



Date of 
infecting 



Date of 
first sec- 
ondary 
case. 



Inter- 
val in 
days. 



Next sec- 
ondary 
case. 



Number 
of second- 
ary cases. 



Orwood, Miss.. 

Do 

Do 

Do 

Do 

Do 

Do 

Do 

Do 

Do 

Do 

Do 

Taylor, Miss. . 

Do 

Do 

Edwards, Miss. 



29 



S9S 



S98 
^9S 



897 



Aug. 
Aug. 

...do 

Aug. 31 

...do 

Sept. 3 
Sept. 17 
Aug. 31 
Sept. 4 
Sept. 25 
Sept. 2 
Aug. 29 
Aug. 7 
Aug. 17 
Aug. 10 
Aug. 8 



Aug. 23 
Sept. 13 
Sept. 18 
Sept. 29 
Sept. 20 
Sept. 26 
Oct. 8 
Sept. 22 
Sept. 20 
Oct. 8 
Sept. 22 
Sept. 9 
Aug. 27 
Sept. 2 
Aug. 25 
Aug. 22 



16i 

15 

20 

29 

20i 

23 

21 

21J 

16 

13 

20| 

20 

16 
15 
14 



Aug. 24 
Sept. 13 
Sept. 18 
Oct. 2 
Sept. 20 
Sept. 30 
Oct. 8 
Sept. 22 



Sept. 3 
Sept. 6 
Aug. 28 
Aug. 26 



1 11 days 15 hours. 

I do not know what conclusion you may draw from the data con- 
tained in Table II, but to my mind they are strongly suggestive that 
the same mode of propagation which we were making use of at Camp 
Lazear during the past winter was at work in the epidemic of yellow 
fever at Orwood and Taylor, Miss., during the summer of 1898. 

From my own personal experience, I can only add one observation 
to those given by Carter, viz, at Quemados, Cuba, where of two 
nurses who remained continuously in attendance upon a case of yellow 
fever, one contracted the disease on the fourteenth day and the other 
on the fifteenth day after the commencement of the primary case. 

While the temptation is great to extract from the literature other 
observations confirmatory of those given (and they are numerous), I 
must refrain from doing this, since I promised to confine myself largely 
to my own experience in regard to the propagation of yellow fever. 
For this reason and because I feel that I have already trespassed 
on your patience longer than I had any right to do, I must omit any 
reference to the habits of culex fasciatus , or of the thermal influences 
concerned in the propagation of this mosquito, both of which are of 
much importance in connection with the subject under consideration. 



108 YELLOW FEVER. 

I trust that I have said enough, however, to indicate to you that, in 
my opinion, the ideas which we have heretofore held concerning the 
propagation of yellow fever must undergo considerable recasting. 
1 do not believe that we can longer ascribe with confidence any part 
of the spread of this disease to fomites, for under such conditions of 
intimate and long-continued exposure as could never occur in the 
natural course of every-day life we have looked in vain for its 
development. 

While in matters pertaining to the public health, cleanliness should 
always stand next to godliness, I do not think that we will be justified 
in assigning so much importance hereafter to those insanitary condi- 
tions of soil which, being due especially to pollution with animal 
matter, were supposed, in some mysterious way, to aid in the spread 
of this disease. Strange as it may sound, I do not believe that the 
enforcement of the most rigid hygienic regulations, such as we have 
heretofore known them, will prevent the propagation of this grave 
epidemic disease, provided it should again be imported into this coun- 
try. I seriously doubt if we can longer class yellow fever with the 
" filth diseases." The apparent results obtained by the improved 
sanitary arrangements instituted by Gen. Butler in the city of New 
Orleans, during the year 1862, and carried on by his military suc- 
cessors, probably served to strengthen, as much as anything else, the 
view held by the profession that filth was, if not essential, yet of 
extreme importance, in aiding the spread of yellow fever. I dare 
say that but few stopped to consider that Gen. Butler found the city 
of New Orleans already quite free of yellow fever, and that the same 
system of blockade which kept this disease out of the former city, 
under improved sanitary conditions, kept it out of other Southern 
seaports during the same period, although their sanitary conditions 
remained unchanged. If one is inclined to believe that improved 
hygienic conditions, as usually understood, will arrest the spread of 
yellow fever, let him turn to the city of Habana under American sani- 
tary administration. Probably in no city in the world have such 
unremitting sanitary efforts been put forth as in the city of Habana 
since our occupation in January, 1899. We were told that the hard 
work of Gen. Ludlow and his assistants was responsible for the marked 
decrease of cases of yellow fever during the first seven months of 1899 — 
and appearances seem to indicate as much — nevertheless, with the 
commencement of Spanish immigration, during August of that year, 
and the introduction of susceptible material, cases of yellow fever 
began to rapidly multiply, so that the city had a late summer and fall 
epidemic of this disease. Concerning the occurrence of yellow fever 
in that city during the past year, Maj. Harvard, chief surgeon, Depart- 
ment of Cuba, in a recent report, after describing the thorough work 
which had been done by the sanitary authorities and its marked effect 
upon the reduction in deaths, especially from tuberculosis, goes on to 
say: 

It is certain tr^it in Habana, in 1900, no visible correlation could be seen between dirt 
and yellow fever; the district which became first strongly infected lies east and south 
of the Parque Central, and is one of the cleanest and best constructed, while the most 
insanitary wards became infected late in the season and only to a slight extent; the 
malodorous district reserved to houses of ill-fame hardly had a case._ Yellow fever has 
not followed the poor and unclean, nor the mark of previous infection, but rather the 
movement of nonimmunes; wherever these located, there the infection searched and 
found them, regardless of the hygienic conditions of their premises. 



YELLOW FEVER . 109 

What is the sanitary story, then, for the year 1900? Simply that 
with the return of summer weather and the continued influx of new 
material, and in spite of unremitting efforts to keep the city clean, 
Habana has experienced a more serious epidemic of yellow fever, 
affecting its civilian population, than it has had during the preceding 
20 years. Xeed we now express surprise at such a result ? Have we 
not seen at Camp Lazear, under the very best hygienic surroundings, 
six individuals attacked with yellow fever, after a few short visits to a 
new building whose foundation stood on the unbroken turf and whose 
rooms were filled with sunshine and with an atmosphere just swept 
in from the ocean, at the very moment of infection? Where then, 
gentlemen, shall we look for the agent that is vitally concerned in the 
propagation of yellow fever ? In the light of these newer observations 
which I have had the pleasure of presenting to you, I believe that we 
may affirm, with some degree of confidence, that here, substituting 
culex for anopheles, we have to deal with the same source of infection 
to which we now trace the malarial fevers — the mosquito. 



Chapter 5. 

EXPERIMENTAL YELLOW FEVER. 1 

By Walter Reed, M. D., Surgeon, United States Army., James Carroll, M. D., 
and A. Agramonte, M. D., Contract Surgeons, United States Army. 

Subsequent to the presentation of our paper to the Pan-American 
Congress 2 in Habana, we succeeded in producing some additional 
cases of yellow fever at our experimental sanitary station near Que- 
mados, Cuba. We have thought that brief reports of these cases, to 
be followed by remarks on experimental yellow fever from the clinical 
point of view, would be of interest to the members of this association, 
and especially to those who reside in sections of the country where 
each year yellow fever is liable to appear in epidemic form. 

Perhaps it .might be well to recall the fact that the cases of yellow 
fever here to be recorded were produced like those heretofore reported 
by us, under strict quarantine regulations and at a special experi- 
mental sanitary station, near the town of Quemados, Cuba. 

In a series of 12 experimental cases produced at this camp during 
the period from December 5, 1900, to February 7, 1901 — an interval 
of 65 days — it should be borne in mind that the order of occurrence 
exactly correspond with the order of inoculation, except that Case II, 
inoculated at 4 p. m., December 8, 1900 — having a longer period of 
incubation than Case III, inoculated at 10.30 a. m., December 9, 
1900 — the order of their relative occurrence became reversed 3 . 
Moreover the attack always followed within the period of incubation 
of the disease, and concerned only those nonimmune individuals who 
had consented to submit themselves for experimentation. Of a total 
of 16 individuals who thus consented, 14 contracted yellow fever; 
whereas of 5 nonimmunes, who did not consent and were therefore 
not subjected to experimentation, none acquired the disease, although 
otherwise placed under exactly similar surroundings. In its occur- 
rence, therefore, at this station, yellow fever strictly obeyed the 
behests of the experimenters, both as to place and time of occurrence. 
Recovery took place in all cases. 

(a) cases produced by the injection of blood. 

Case I. — W. J., American, nonimmune, aged 27 — in quarantine since December 
20, 1900 — with his full consent, at 11 a. m., January 4, 1901, was injected subcuta- 
neously with 2 c. c. of blood taken from the general circulation of a case of mild yellow 
fever at the beginning of the second day of the disease and having a temperature of 
100.8° F. The subject, who had been in strict quarantine at the station for the period 
of 45 days, remained in his usual health until the early morning of January 8, when 
he complained of slight frontal headaches. At 6 a. m. his temperature was 98.2° F., 
and pulse 70; 9 a. m., temperature 99.8° F., pulse 95; frontal headache increased, with 

i Read before the Sixteenth Annual Meeting of the Association of American Physicians, held at Wash- 
ington, April 30, May 1 and 2, 1901. 

2 The Etiology of Yellow Fever. An Additional Note. Read at the Pan-American Congress, Habana, 
February 4-7, 1901. 

3 These cases were reported in our Additional Note. 

110 



YELLOW FEVER. 



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112 YELLOW FEVER. 

slight chilly sensations in the feet and lower extremities. There were some con- 
gestion of the eyes and his usual florid complexion was heightened in color. At 
10.15 a. m., temperature 100.6° F., pulse 97. Complains of some pain in the lumbar 
region. At 11.20 a. m., temperature 101.4° F., pulse 99. The height of the febrile 
paroxysm was reached at 3 p. m. the same day, when the temperature was 103.4° F. 
and pulse 108. The facial expression was now characteristic of yellow fever. The 
eyes were deeply injected and watery and the face much suffused. Photophobia 
moderate — frontal headache and backache severe. The skin was moist. The 
remission occurred at the end of 24 hours — 9 a. m. January 9 — when the temperature 
had fallen to 99.4° F. and the pulse to 86. The subsequent history was that of a case 
of yellow fever of moderate severity. Albumin was found in the urine at the end 
of the sixty-first hour. There was some bleeding from the gums on the third day 
and moderate ocular jaundice on the fourth day. Fever disappeared on the morning 
of the seventh day. (Chart I.) 

Case II. — W. O., American, nonimmune, aged 28, in quarantine since December 
20, 1900. On January 8, 1901, at 9 p.m., with his full consent, he was given by sub- 
cutaneous injection 1.5 c. c. of blood taken from the mediancephalic vein of Case I, 
just 12 hours after the beginning of the attack and when the temperature was 102.4° F., 
that is, just after the first febrile paroxysm began to decline. The subject remained 
in his usual condition during the following two days. 

January 11, 1901, at 6 a. m. his temperature was 98.9° F. and pulse 70. He com- 
plained of being disturbed by dreams during the night and had some frontal headache. 
At 9 a. m. temperature 100° F., pulse 77. At 10.15 a. m. temperature 101.4° F., pulse 
76. Eyes decidedly congested and face moderately suffused. At 12 o'clock noon, 
when the temperature had risen to 103.2° F. and the pulse to 102, the height of the 
primary paroxysm had been reached. Headache and backache were now much 
complained of. The facial expression was characteristic. The remission occurred 
at the end of 24 hours, lasted one day, and was followed by a very moderate secondary 
fever. A distinct trace of albumin was found in the urine passed at 2 a. m. January 
12, 17 hours after the attack began. A few hyaline casts were also present. Slight 
bleeding from the gums occurred on the second and third days of sickness. The 
character of the attack in this case was vey mild. The albumin, which at no time 
amounted to more than a distinct trace, did not disappear, however, until January 
24. (Chart II.) 

Case III. — W. F., American, nonimmune, aged 23, was, with his full consent, at 1 
p. m. o'clock January 22, 1901, injected subcutaneously with 0.5 c. c. of blood taken 
on the second day from the general circulation of a severe case of yellow fever, which 
was fatal on the seventh day of the disease. The patient's temperature, when the 
blood was withdrawn, was 103° F. and pulse 90. The subject remained well during 
the following day. January 24, at 6 a. m., his temperature was 98.4° F., and pulse 
78. He partook of a hearty breakfast at 6.30 a. m., which he vomited soon afterwards. 
At 7 a. m. he complained of dizziness and general lassitude. Temperature, 98.4°, 
pulse 78. At 9 a. m., chilliness complained of, but there is no record of temperature 
or pulse. At 9.30 a. m., temperature 100.6° F., pulse 82. Frontal headache well 
marked. Eyes already injected and face slightly suffused. At 10.30 a. m., tempera- 
ture 101.2° F. and pulse 86. An hour later his temperature was 102.6° F. and pulse 
82. The height of the primary paroxysm was reached at 1 p. m. when the tempera- 
ture was 102.8° F. and pulse 98. At this hour photophobia was well marked and 
constant complaint made of severe frontal headache and backache, together with 
pains in the lower extremities. The skin was moist. The remission occurred at the 
end of 36 hours. The subsequent course was that of a case of yellow fever of moderate 
severity. With the return of the secondary fever there were present sharp backache 
and headache. Albumin appeared in the urine at the end of 57| hours. Ocular 
jaundice was present on the third day and thereafter until convalescence. The gums 
did not bleed, although they were swollen and injected. Fever subsided on the sixth 
day, and albumin disappeared on the eighth day. (Chart III.) 

Case IV. — J. H. A., American, nonimmune, aged 22, with his full consent, received 
subcutaneously, at 12.15 p. m., January 25, 1901, 1 cc. of blood taken from the median- 
cephalic vein of Case III, just 27J hours after the commencement of the latter's attack 
of yellow fever (T. 100.6° F.). The subject remained in his usual condition during 
January 26 and 27, except that on the afternoon of the last-mentioned date he com- 
plained of occipital headache. This was present on the following morning, January 
28; otherwise he felt well. His temperature at noon was 98.6° F., and pulse 68. 
Occipital headache continued. He partook of dinner with fair appetite. He was not 
seen again until 3 p. m. In the meanwhile, at 1.15 p. m., the subject states that, 
while sitting alone in his tent, he began to feel cold, and that this was quickly fol- 
lowed by a decided chill with increase of headache. He noted the hour in writing at 



YELLOW FEVER. 



113 



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79965°— S. Doc. 822, 61-3- 



114 YELLOW FEVEE. 

the time. At 3 p. m. his temperature was 103.6° and pulse 120. The eyes were 
intensely congested and the face deeply suffused. The patient was very restless, and 
complained bitterly of occipital headache and backache. Photophobia was very 
marked. He vomited several times within the next 2 hours. Skin hot and dry. 
The height of the primary paroxysm was reached at 3.30 p. m., at which hour the 
temperature was 104.2° F., and pulse 120. The subsequent history was one of severe 
yellow fever. There was no remission in the fever until the fourth day, when the 
temperature fell to 101.2° F. Now, for the first time, the patient ceased to complain 
of occipital headache and backache. Albumin appeared at the end of 18| hours 
(7.30 a. m., January 29). A few hyaline casts were also present at this time. The 
specimen of urine passed at 6.40 a. m., January 30, contained albumin one-twentieth 
by volume, and many fine and coarse, granular, bile- tin ted casts. Ocular jaundice 
appeared on the third day. The skin of the face and of the anterior part of the neck 
and thorax was tinted on the fourth day. This rapidly became intensified and general. 
The secondary fever lasted about 30 hours, the temperature falling to 97.2° F. at 12 
o 'clock (midnight) of the fifth day. Marked fluctuations of temperature continued 
until the eleventh day of illness. Recovery was slow and much delayed by the 
development of a carbuncle in the left sacral region. A trace of albumin was still 
present on March 1, 32 days after the attack had begun. (Chart IV.) 

The production of yellow fever by the injection of blood taken 
from the general circulation is of much interest as showing, first, 
that the parasite is present in the blood, at least during the early 
stages of the disease, and secondly, that its passage through an inter- 
mediate host, although this would seem to be nature's method, is not 
essential in the life cvcle of this parasite. Thus yellow fever is 
analogous to the malarial fevers, in that it may be produced either 
by the bite of a certain species of mosquito, or by the injection of 
blood taken directly from the general circulation. 

Another point to which we have elsewhere referred, but which is 
considered of sufficient importance to bear repetition here, is that in 
each of the foregoing cases of experimental yellow fever produced by 
the injection of blood, careful cultures made from the same blood 
drawn from the vein immediately after injection or, as in one instance, 
made from the same syringeful of blood that conveyed the disease, 
failed to show the presence of Sanarelli's bacillus. In one case colo- 
nies of Staphylococcus pyogenes citreus were obtained, while in the 
remaining three cases no growth whatever occurred. The exclusion 
of Bacillus icteroides from further consideration as the specific agent of 
yellow fever would, therefore, seem to have been conclusively deter- 
mined by these experiments. 

(b) cases produced by the bite or THE mosquito, culex fasciatus. 

Case V. — L. F., American, nonimmune, aged 28 — in quarantine since December 20, 
1900 — was, with his full consent, at 3.30 p. m., January 19, 1901, bitten by three mos- 
quitoes that had been contaminated 39 days previously, by feeding on the blood of a 
well-marked case of yellow fever, on the third day of the disease. The subject 
remained in his usual condition of health until the afternoon of January 23. At noon of 
this date his temperature was 97.8°. Soon after this hour he took to his bed, com- 
plaining of frontal headache and general lassitude. At 3 p. m. his temperature was 
99.2° and pulse 78. At 4.10 p. m. the temperature was 100° F. and pulse 104. A 
sense of chilliness, especially of the lower extremities, and increased frontal headache, 
were now complained of. Eyes already injected and face flushed. At 5 p. m. the 
temperature was 101.2° F. and pulse 104. The height of the paroxysm was reached at 
8.20 p. m., at which hour the temperature was 103.6° F. and the pulse 110. The eyes 
were deeply congested and photophobia very marked. Headache and backache were 
so intense as to cause the patient to complain bitterly. He vomited once at 9 p. m. 
January 24, 3 a.m., the temperature had fallen to 100.2° and the pulse to 104, but with 
only slight amelioration to the patient's discomforts. At noon the thermometer 
marked 102 ° . Remission occurred at the end of 33 hours , with marked diminution of all 
disagreeable symptoms. The secondary fever, attended by increased headache and 



YELLOW FEVER. 



115 



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116 YELLOW FEVER. 

backache, lasted four days, the temperature dropping to normal at 6 p. m. of the 
seventh day. The case was one of moderate severity. Albumin appeared in the 
urine at the end of the forty-second hour. Ocular jaundice was quite noticeable on 
the afternoon of the second day. Some jaundice of the face and anterior region of the 
chest was seen on the fourth day. Many bile-tinted granular casts were present in the 
urine on the third day, and thereafter until the eleventh day. The albumin which 
reached one-fifteenth by volume on the sixth day disappeared on the twelfth dav. 
(Chart V.) y 

Case VI. — C. W., American, nonimmune, aged 27, with his full consent, was at 
9.30 a. m., January 31, bitten by 2 of the 3 mosquitoes that had been applied to the 
foregoing Case V. The interval that had elapsed since their contamination was, 
therefore, 51 days. The subject remained well until 12 o'clock noon, February 3, 
when he complained of heaviness in his legs and some supraorbital pain. His tem- 
terature at this hour was 99° F. and pulse 70. At 1.30 p m. it had risen to 100° F., 
and at 5 p. m. to 100. ° F. and pulse to 84. The primary rise of fever, which was some- 
what fluctuating in character, did not reach its height until at the end of 24 hours, 
noon, February 1, when the temperature was 102.4° and the pulse 92. The facies 
was now suggestive of yellow fever. Remission occurred at the end of 45 hours and 
lasted for about 1 day. The secondary rise was slight in character, the temperature 
falling to normal on the morning of the sixth day. The case was very mild in char- 
acter. Albumin appeared at the end of 75 hours (beginning of fourth day); it never 
amounted to more than a distinct trace and disappeared on the eighth day. There 
was no ocular jaundice, and although the gums were injected and swollen, there was 
no hemorrhage at any time. The patient perspired freely throughout the attack. 
Convalescence was rapid. The subject had been in quarantine for the period of 6 
days prior to inoculation. (Chart VI.) 

Case VII. — J. H., American, nonimmune, aged 26, with his full consent, was bitten 
at 11 a. m., February 6, 1901, by the same 2 mosquitoes that had 6 days previously 
bitten Case VI. Fifty-seven days had therefore elapsed since the insects had been 
contaminated by biting a case of yellow fever. He remained well until 12 o'clock 
noon^ February 9, when lie experienced slight chilly sensations, accompanied by 
yawning. At this hour his temperature was 99° F. and pulse 72. At 3 p. m., tem- 
perature 98.8°, pulse 72. Says that he feels "out of sorts," but has no headache. At 
5.30 p. m. his temperature was 100.6° F., pulse 78. He was not seen until 7.30 p. m., 
when he complained of backache and severe general headache, more intense through 
the frontal region. Eyes much injected, photophobia very marked, face flushed. 
He was stretching and yawning constantly, complained of nausea, and vomited a 
small quantity of partially digested food . The height of the primary fever was reached 
at 3 p. m., February 10, i. e., 22 hours after the commencement of the attack, when 
the temperature was 102.8° and the pulse 98. Remission of the fever to 99.4° and 
pulse to 74 occurred at 6 a. m., February 11, making the duration of the primary 
paroxysm 36 hours. Twenty-four hours after the remission had occurred the tem- 
perature had risen to 102.4° with a pulse of 70. The fever continued to steadily 
increase until midnight of February 12, when a temperature of 105° F. was recorded, 
with a pulse of 90. The subsequent course was that of a case of severe yellow fever. 
Slight oozing of blood from the gums occurred as early as the third day. Ocular 
jaundice, beginning on the third day, became later very distinct and was associated 
with general jaundice. Albumin, however, did not appear until the sixth day. The 
fever subsided on the ninth day, and was followed by a slow convalescence. The 
subject had been in strict quarantine for a period of 78 days prior to inoculation. 
(Chart VII.) 

Case VIII. — C. S., American, nonimmune, aged 28, with his full consent, was 
bitten at 2 p. m., February 7, 1901, by 3 mosquitoes that had been contaminated 
16 days previously by biting a fatal case of yellow fever on the second day of the 
disease. The subject remained well until the early afternoon of the third day, Feb- 
ruary 10. He ate his dinner at noon with good appetite. At lp.m., his temperature 
was 100° F., pulse, 90. Frontal headache was now complained of. This became 
rapidly more marked, and pains in the limbs were also present. Three hours later, 
4 p. m., the fever had risen only one-fifth of a degree, but at 6 p. m. it had reached 
103° F. and pulse, 96. At this hour he had severe headache and backache, with 
general pains over the body. The facial expression was now characteristic. Eyes 
brightly injected, photophobia well marked, and face decidedly congested. At 9 
p. m. temperature was 103.2° and pulse 112. The skin was moist. Remission occurred 
at 6 a. m., February 12, 41 hours after the commencement of the febrile paroxysm. 
The secondary fever, which was moderate in character, lasted 4 days, the fever sub- 
siding on the seventh day. Ocular jaundice was slight. A few hyaline casts were 
present on the third and subsequent days, but no albumin was found until 1 p. m., 



YELLOW FEVER. 



117 





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118 YELLOW FEVEK. 

February 18, that is, 36 hours after the fever had subsided. It was present at a dis- 
tinct trace in all specimens examined until 3 p.m., February 23. Convalescence was 
rapid. The subject had been in quarantine for a period of 25 days prior to inocula- 
tion. (Chart VIII.) 

The foregoing cases of experimental yellow fever (Cases V, VI, and 
VII) are, we think, of especial importance as showing the length of time 
during which the mosquito may remain capable of conveying the infec- 
tion. In previous papers we have reported 6 cases of yellow fever pro- 
duced by the bites of mosquitos at intervals varying from 12 to 24 days 
after the contamination of the insects. In the cases here reported 
the periods intervening between the contamination of the insect and 
the production of the disease were much longer, viz, 39, 51, and 57 
days, respectively. As one of these insects lived until the sixty-ninth 
and another until the seventy-first day after contamination, we have 
for the first time an explanation of the fact, several times noted in 
the literature, that the contagion of yellow fever may cling for several 
months to a building that has been vacated by its occupants, or to 
the infected area of a town, even though this latter has been entirely 
depopulated. These particular insects also were contaminated at a 
later stage of the disease than in any of our other cases, i. e., on the third 
day and during the secondary rise of the fever, following a complete 
intermission in the temperature. We have, therefore, been able to 
demonstrate that the parasite is present in the general circulation 
both after and before the stage of remission. How much later in the 
disease the parasite may still be found — a matter of much interest 
and importance — the observations thus far made do not determine. 
Although the 3 mosquitoes applied on the third day, as above stated, 
acquired the parasites and were able to affect 3 individuals with yellow 
fever, a single mosquito applied to the same case of yellow fever on 
the fourth day of the disease failed to obtain the parasite, as shown 
by the negative result following its bite 40 days after contamination. 
That not all mosquitoes become infected, however, with the parasite 
by biting yellow fever patients is shown by several observations made 
by us. We submit only one. 

Case IX. — J. W., American, nonimmune, was, with his full consent, on January 
25, 1901, bitten by 12 mosquitoes (C '. fasciatus) that had fed on a case of mild yellow 
fever — in a man named Martinez — on January 3, 1901, within 8 hours of the com- 
mencement of the attack. Although these mosquitoes had been kept at a summer 
temperature for 22 days, the result of the experiment was entirely negative. That 
the parasites were present in Martinez's blood at the end of 24 hours was fully shown 
by the effect produced by injecting 2 c. c. of his blood drawn at this time beneath the 
skin of Case I of this report. 

Observations such as the foregoing would indicate that the mos- 
quito at certain periods of the disease may fail to obtain the parasite, 
owing to its absence at that particular time from the capillary circu- 
lation. Concerning the matter of the propagation of yellow fever 
by other species of culex than C. fasciatus, we have only 1 negative 
observation to record of an individual bitten by 5 C. pungens that 
had been contaminated by biting a case of yellow fever 19 days pre- 
viously. To a single negative experiment such as this no importance 
can be given, so that this question must be left for future observa- 
tions to determine. 

Touching the subject of the possible transmission of the parasite 
to the daughter insect by means of infection of the ovum, we have 
also but a single observation to record. In this case the bites of 14 



YELLOW FEVER. 



119 





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120 YELLOW FEVER. 

mosquitoes, hatched from the ova of a mosquito (C.fasciatus) that had 
already shown itself capable of conveying the disease, were followed 
by an entirely negative result. 

Including the cases heretofore reported by us, we have thus far 
succeeded in conveying yellow fever to 12 individuals by means of 
the bites of contaminated mosquitoes, and to 4 other persons by sub- 
cutaneous injection of blood taken from cases of this disease — a 
total of 16 cases. While ordinarily. so small a number of cases would 
not be sufficient to enable one to arrive at definite conclusions con- 
cerning the general character and course of an acute infectious 
disease, the conditions under which the majority of these cases were 
observed were such as to give us valuable data concerning two 
matters of very great practical importance in connection with this 
disease, viz, the period of its incubation and the difference in degree 
in the character of its attacks. Further, as these cases were kept 
under constant observation, even from the time of inoculation, we 
are not only able to report upon the earliest premonitory symptoms, 
but also to give the primary temperature curve; and, in addition, to 
note the time of appearance of albumin in the urine, all of which are 
of interest in the clinical history of yellow fever. 

Period of incubation. — The accurate determination of the period 
of incubation of any one of the acute infectious diseases is always a 
matter of scientific interest. If the disease is one which, like yellow 
fever, is of exotic origin and whose importation is liable to give rise 
to a widespread epidemic, then the determination of its incubative 
stages becomes of the highest practical importance. This importance, 
as a question of public hygiene, is increased, if as recent observations 
would seem to indicate, the importation of this disease is brought 
about only by the sick individual and not by his baggage or clothing. 
While the older authors were willing to prolong the period of incuba- 
tion of yellow fever to 2 or 3 weeks or even longer, the tendency of 
physicians at the present time is to shorten this stage to about 5 days. 
^Reference to a few of the later text-books on the Practice of Medicine 
will sufficiently indicate this. Davidson, in Allbutt's System, 1 puts 
down the period of incubation as " ranging between 24 hours and 4 
or 5 days." Stevens 2 says that it may vary from "a few hours to a 
week." Osier 3 says that "the period of incubation is usually 3 or 4 
days, but it may be less than 24 hours or prolonged to 7 days." 
According to Tyson, 4 " yellow fever has a period of incubation of 
from 24 hours to 5 days, very rarely exceeding the latter." Stern- 
berg 5 says that this period "does not usually exceed 4 or 5 days and 
may be less than 24 hours." Carter, 6 in a recent valuable paper, 
gives the results of his studies on the period of incubation of yellow 
fever, based on observations extending over a considerable number 
of years. Under Class III of his observations, which are the most 
valuable, he includes "those persons who, living in a clean environ- 
ment, go into an infected one, stay only a short time, and then return 
to a clean environment where they remain until the fever develops." 

i A System of Medicine, London, 1897, Vol. II, p. 394. 

» Practice of Medicine, Philadelphia, 1898, p. 286. 

a The Practice of Medicine, New York, 1899, p. 185. 

< Practice of Medicine, Philadelphia, 1900, p. 85. 

'Buck's Reference Handbook of the Medical Sciences, 1889, Vol. Ill, p. 58. 

6 The Period of Incubation of Yellow Fever, New York Medical Record, March 9, 1901. 



YELLOW FEVER. 



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YELLOW FEVER. 



123 



Of 12 cases thus accurately observed by himself the incubative stage 
was as follows: 





Days' 


Cases. 


incuba- 




tion. 


2 


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3+ 


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51 


12 



The following table gives the result of our observations in 16 cases 
of experimental yellow fever. 

Table I. — Period of incubation of experimental yellow fever. 



^ase° f Date of tooc^ati 011 - 


Method of inocu- Date of commencement of 
lation. attack. 


Incubation 


1 | Aug. 27, 1900, 2 p. m 

2 A mr. 31. 1900. 11 a. m 




Aug. 31, 1900, 9 a. m 


Dys. hrs. 
3 7 


do 


Sept. 6, 1900, lp.m 


6 2 


3 

4 


Dec. 5, 1900, 2 p. m 

Dec. 8, 1900, 4 p. m 

Dec. 9, 1900, 10.30 a. m 

Dec. 11, 1900, 4.30 p. m 

Dec. 21, 1900, 12 noon 

Dec. 30, 1900, 11 a. m 

Jan. 4, 1901, 11 a. m 


do 

do 

do 

do 

do 

do 

Blood injection 

do 

Mosquito 

Blood injection 

do 

Mosquito 

'.V^Ao'.'." '.'.'.'.'.'.'.'. . 


Dec. 8, 1900, 11.30 p. m 

Dec. 14, 1900, 9 a. m 


3 9h 
5 17 


5 
6 


Dec. 12, 1900, 9.30 p. m 

Dec. 15, 1900, 12 noon 


3 11| 

3 19J 
3 23 


7 


Dec. 25, 1900, 11 a. m 


8 


Jan. 3, 1901, 10.30 a. m 


3 22J 

3 22 


9 


Jan. 8, 1901, 9 a. m 


10 


Jan. 8, 1901, 9 p. m 

Jan. 19, 1901, 3.30 p. m 

Jan. 22, 1901, lp.m 


Jan. 11, 1901, 9 a. m 


2 12 


11 


Jan. 23, 1901, 3 p. m 


3 23* 


12 


Jan. 24, 1901, 9 a. m 


1 19 


13 
14 


Jan. 25, 1901, 12.15 p. m 

Jan. 31. 1901. 9.30 a. m 


Jan. 28, 1901, 1.15 p. m 

Feb. 3, 1901, 12 noon 


3 1 
3 2h 


15 Feb. 6, 1901, 11 a. m. 


Feb. 9, 1901, 5 p. m 


3 6 


16 Feb. 7. 1901. 2 n. m 


Feb. 10, 1901, 12 noon 


2 22 




' r 







The average period of incubation of the 16 cases embraced in 
Table I will be found to be 87^ hours, or 3 days 15J hours. If we 
separate the 12 mosquito infections from the 4 cases produced by the 
injection of blood, we have for the former a period of incubation of 
94 hours or 3 days and 22 hours, and for the latter an incubative 
stage of 67-J hours, or 2 days 19^- hours. The average period of incu- 
bation, therefore, in the cases brought about by subcutaneous injec- 
tion of blood was shorter by 26^- hours than those occasioned by the 
mosquito's bite. By the former method, this stage varied from 43 
hours to 94 hours, while in the mosquito infections the shortest incu- 
bative period was 70 and the longest 146 hours. If we accept those 
cases produced by the mosquito's bite as the usual method of propa- 
gation of this disease, it will be observed that of the 12 cases 1 occurred 
on the third day, 9 on the fourth day, 1 on the sixth day, and 1 at 
the beginning or the seventh day after incubation. 

While our results, therefore, confirm the statement of later writers 
that the period of incubation of yellow fever does not usually exceed 
4 or 5 days, they also seem to indicate very plainly that this stage 
may be prolonged more frequently, perhaps, than had been supposed. 

In 16.6 per cent of our cases the period of incubation exceeded the 
usual quarantine period of 5 days. If we add Carter's cases to those 
observed by us, we rind that of 24 cases the period of incubation 



124 



YELLOW FEVER. 



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YELLOW FEVER. 125 

exceeded 5 days in 3, or 12.5 per cent. We will not further dwell 
on this subject than to remark that cases No. 2 and No. 4 of our series 
could have passed quarantine on the morning of the sixth day 
after inoculation, with a clinical thermometer under the tongue, with- 
out exciting any suspicion by reason of the presence of fever. 

Character of the attack. — We desire to call attention particularly to 
the difference in the degree of severity of the attack as shown by our 
experimental cases. Like all of the other acute infectious diseases, 
we have reason to expect that yellow fever will affect different indi- 
viduals according to their individual susceptibilities, and hence that 
we will encounter mild as well as severe cases. The results which 
we have obtained confirm this expectation. Based upon the char- 
acter of the attack, the 12 cases due to mosquito inoculation may be 
divided as follows: 

Severe .■ 2 

Moderately severe 6 

Mild., 3 

Very mild 1 

12 

The 4 cases produced by the injection of blood gave the following 
result : 

Severe 1 

Moderately severe 2 

Mild 1 



Thus the cases which were mild or very mild in character consti- 
tuted 33 per cent of those infected by the mosquito's bite and 25 of 
those produced by blood injection. It is to the diagnosis of the former 
cases that we desire to direct special attention. To one familiar with 
yellow fever, or even to one unfamiliar with its clinical features, the 
diagnosis of our severe and moderately severe cases should have pre- 
sented no difficulty. The sharp headache and backache, the charac- 
teristic facies, the ocular jaundice, together with the presence of albu- 
min in the urine, except in 1 case to be hereafter referred to, with the 
negative result of a blood examination, would have been a sufficient 
complex of symptoms to have rendered the diagnosis tolerably certain. 
Even in our 3 "mild" cases, were the physician on his guard and 
acquainted with the temperature curve and pulse from the very onset 
of the attack and, besides, careful in the testing of each specimen of 
urine passed, a diagnosis of yellow fever could have been made with 
reasonable probability. We believe, however, that, in the ordinary 
course of events, where there was no reason to suspect the presence 
of yellow fever the average practitioner would have probably failed 
to appreciate the true nature of these attacks. Such was the admis- 
sion which we ourselves were compelled to make, although in con- 
stant attendance and thoroughly acquainted with these cases from 
their very beginning. The short duration of the primary fever in one 
instance; the rapid amelioration of the earlier symptoms in all; the 
absence of albumen during the first 3 days, or its presence, as a mere 
trace, in certain specimens, followed by its absence in succeeding 
specimens; the slight icteroid hue of the conjunctiva — to be obtained 
only in a certain light and then doubtfully — all served to render a 



126 YELLOW FEVER. 

positive diagnosis exceedingly difficult. Several physicians, who saw 
these milder cases at our request, readily acknowledged the improba- 
bility of a correct diagnosis being made in the absence of the complete 
data which we were able to furnish concerning them. In the one case 
which we have classed as "very mild" yellow fever we believe that 
the matter of a correct diagnosis would have been in the highest de- 
gree improbable. The attack consisted of a single paroxysm of 33 
hours' duration, during which the temperature only reached 101° for a 
period of 6 hours. It is true that albumin was found in the urine at 
the end of 37 hours, but the quantity was exceedingly small and only 
to be detected by the most delicate testing. It was only present in 1 
or 2 specimens passed on the third day. A slight trace was present in 
a specimen passed at 9 a. m. of the fourth day and in that passed at 
4.40 p. m. of the fifth day. Intervening specimens of urine, several in 
number, contained no albumin. A well-marked papular eruption 
which appeared on the fourth day of the disease, and which was con- 
fined to the trunk and arms, would hardly have rendered the diag- 
nosis easier. We suppose that during the prevalance of an epidemic 
of yellow fever a physician who was thoroughly acquainted with the 
several types of this disease would probably class this case as one of 
extremely mild yellow fever, with a wide margin for doubt. Under 
all other circumstances we feel confident that cases of this character 
would escape diagnosis. That cases of mild yellow fever may and do 
serve as foci for the development of other cases our own observations 
demonstrate, since we have been able to propagate the disease from one 
such mild case by means of the bites of contaminated mosquitoes, and 
from another case of like character by the subcutaneous injection of 
2 c. c. of blood. 

THE ONSET AND PREMONITORY SYMPTOMS. 

Of the 12 cases produced by mosquito inoculation, the onset was 
sudden in 2 and gradual in 10. In both of the former the attack 
occurred during the night, the patient, also, in both instances, being 
awakened by the occurrence of a decided chill. In 1 of the 2 cases of 
sudden onset, the subject complained of slight supraorbital headache 
during the afternoon preceding the attack. Of 4 cases produced by 
the injection of blood, the onset was sudden in 1 — the only case 
marked by a chill — and gradual in 3. The attack in all of these 
blood cases began during the daytime. As writers generally state 
that in yellow fever the chances of infection are greater during the 
night, we have thought that, perhaps, the time of inoculation of our 
experimental cases (which was during the day except in 1 instance), 
might have had some influence upon their occurrence, as a rule, 
during the daytime. If the hour of inoculation in all of our cases 
should have taken place at about sunset, then, with the same period 
of incubation, 7, or 43 per cent would have experienced their attacks 
at night. 

Of the 13 cases in which the onset was gradual — by mosquito 
inoculation, 10; by blood injection, 3 — frontal headache, the pain 
being referred to the supraorbital region and extending into the 
temporal region, was the most frequent premonitory symptom. It 
was present in 10 and absent in 3 cases. This symptom preceded 
the attack in these cases at intervals varying from 2 to 48 hours. 



YELLOW FEVER. 127 

In 2 cases no premonitory headache was complained of, while in 1 
case occipital headache preceded the onset by 24 hours, and con- 
tinued to be of this character throughout the attack. Dizziness was 
complained of by 3 of the gradually developing mosquito cases, and 
a sense of weight in the lower extremities by the 2 others belonging 
to this group. All of the cases of gradual onset (13 in number) com- 
plained of lassitude and want of appetite, on which account all took 
to their beds prior to the onset of fever. Ten of these individuals 
complained of slight sensations of chilliness — generally confined to 
the lower extremities — at the beginning of the attack, while in 3 
this symptom was entirely absent. In our experimental cases, 
therefore, frontal headache and muscular debility were the most 
frequent and prominent premonitory symptoms. After the attack 
had developed, the symptoms correspond to those described at 
length by various writers and with which all are familiar, except that 
black vomit did not occur in any of our cases. 

THE FEVER. 

As we have had prepared charts of our several cases of experi- 
mental yellow fever, from which all the data concerning temperature 
and pulse can be obtained, it will not be necessary for us to make 
extended remarks under this heading. Medication being practically 
nil in our cases, both temperature-curve and pulse can be accepted as 
faithfully representing what normally takes place in an attack of 
this disease. When ice water enemas or cold sponge baths were 
used by the attending physician, this is noted on the chart. It 
should also be remembered that our patients were put to bed at the 
very first manifestation of the disease, and carefully transported to 
the yellow-fever wards on the very same beds which they had occu- 
pied in camp. This probably had some effect upon the subsequent 
course of the fever. The record of temperature being taken every 3 
hours from the time of inoculation enables us to give the complete 
curves of both the primary and secondary febrile paroxysm. Our 
charts therefore differ considerably from those given by the various 
writers on yellow fever in that they round out, as it were, the primary 
stage more fully. An examination of these charts will show that 
although the primary rise of temperature is tolerably abrupt and 
reaches its height within a comparatively short time, it does not 
reach its maximum so quickly as the description of writers would 
seem to indicate. The trihourly record in 10 of our mosquito inocu- 
lations shows that this period of primary rise varies from 12 to 24 
hours. In 3 cases it was 12 hours; in 2, 15 hours; in 1, 15 J hours; 
in 1, 20J hours; in 1, 22^ hours; and in 2, 24 hours. The average 
period of the 10 cases was therefore a fraction over 16 hours. 

In striking contrast to these was the short period of the primary 
rise of temperature in the 4 cases produced by blood injection. In 
these it varied from 2\ to 9 hours, the remaining 2 cases giving 6 and 
7 hours respectively, the average for the 4 cases being only 6 hours. 
In all of the 12 cases due to mosquito inoculation, the primary rise of 
temperature was followed by a distinct remission or intermission, 
which was generally reached within 48 hours. The same remission 
was present in 3 of the 4 cases produced by blood injection. We are 



1 _ B YELLOW fLVKK- 

able to give the duration of the primaiy paroxysm accurately in the 
10 cases produced at Camp Lazear by the bites of mosquitos* viz. : 
















- 






-1 




1 as 




;- 


: 


fl 


3 


fi 


I 


: : 


- 




:: 





The average duration of these 10 cases was 43 hours. In the 3 
eases caused by the injection of blood the length of the primary 
paroxysm was 24 hours in 2 cases and 36 hours in 1 case — the average 
being 2S hours. We may therefore say that not only the average 
period of incubation, but also the primary rise of temperature, as 
well as the length of the first febrile stage were all shorter in the 
cases produced by blood injection than in those due to the mos- 
quito's bite. Of the 12 cases due to the latter mode of inoculation 
the first febrile stage was followed by an intermission in 2. and a 
remission in 10 cases. Of those produced by the injection of blood, 
: s^ii'wed a distinct remission and 1 no intervening fall of tempera- 
ture. The duration of this intermission varied from 3 to 27 hours. 
_ his was followed by a second febrilr stage :r paroxysm in 11 of the 
12 mosquito inoculations, and in 3 of the 4 cases due to the injection 
of blood. The duration of this second febrile paroxysm was from 2 
to 5 daj5 

Experimental yellow fever then, as we saw it at Camp Lazear, 
consisted of a primary and secondary febrile paroxysm, with an 
intervening remission or intermission — more frequently the former. 
The secondary was much longer than the primary febrile stage. 

In 1 of our mosquito inoculations a relapse occurred on the ninth 
day of the disease and was characterized also by 2 febrile stages 
with an intervening remission. There were present headache and 
backache, with injection of the ^7= and face, together with hemorr- 
hage from the gums is L; sen /.served in the primary attack. 

T_e want of correlation between temperature and pulse Paget "s 

law), upon which clinicians rely as an important diagnostic sign. 

seen i rule in our experimental cases, i. e.. after the pas- ige 

of the first febrile stage. In 1 case produced by the injection of 

Hood. Faget's law was not complied with. 

The mnme. — We have confined our examination of the urine largely 
to testing for the presence of albumin and to the ordinary microscopic 
examination of this fluid. Heat and nitric acid was the method used 
in all cases for the detection of albumim the specimen having first 
been carefully filtered. 

Under this heading we desire to speak only concerning the pres- 
ence of albumin. All writers dwell on the importance of a careful 
examination of the urine in suspicic of fever, since the pres- 

ence of albumin in the urine is such a constant sign in vellow fever. 
Guitexas, who has had a large experience with this disease, savs: 



YZLI/vr rZV'Z?,. 



1-9 



"The albumin appears in the urine usually on the third or fourth 
day of the disease. It may be very transient. In many mild cases 
the albumin is present only in the urine passed in the evening of the 
third or fourth day. In many cases it is only a trace." We may 
say that the results obtained from examination of the urine of experi- 
mental yellow fever accords for the most part with the statements 
above quoted. 

Table D 



Case. 



1.... 

2.... 
3.... 
4. ... 

5 

6.... 

8.... 

9.... 
10.... 
11.... 
12.... 

13.... 
14.... 
15.... 
16.... 



- oneafap- 

Albumin during period of | p *^t° f 

incubation. hSS^ 

during toe 



Mosquito inoculation : 

DC 

None 

None 

Be 

None 



None 

None 

None 

None 

None 

None 

Blood inoculation: 

None 

None 

None 

None 



Hours. 



m 
i 

n 

■m 
m 
is 

106 
None. 



-:: 

13 



Time of disappearance 
of aJbumi 
from appearance. 



iiirizi-ini : -lantit 



Tenth, day Eigftt-tentfta by Tolume. 

Eleventh, day. TJnee-tentna by volume. 

Fifteenth, day t Two^tentha ";y volume- 
Fifth day Dfetinet trace 

Fourth, day : Lisht trace. 

Third dav". Distinct orace. 

[ay E>o. 

Ninth, day One-fortieth, by volume. 

Twelfth £27 "ne-twentieth. by volume. 

.-/■ E HtfeiDfft trace. 



Thirteenth, day. 
Twelfth, day... 

1 ifteentfiday.. 



: n ~ :' ; i tieth. b y volume . 
One-twentieth, by volume. 

Distinct trace. 
Dol 

Do. 

One-tenth by volume. 



rrt 



In our earlier cases we did not examine for albumin until the 
of the attack. In our last 9 ses (those embraced in this report we 
examined daily specimens from the time of inoculation until the a: : k 
began, and thereafter we endeavored to exa m i n e every specimen 
passed by the patient. Tal le II gives the results obtained. 

An examination of the cases presented in this table will show that 
of the 12 mosquito inoculations the earliest appearance of albumin 
was at the beginning of the second day in 1 3 iring the second 

day in 5 : at the i the s I -7 in 1 ; during the third day in 1 ; 

during the fourth day in 2 ; during the fifth day in 1 ; while in 1 — a 
well-marked case — no albumin could be detected till 36 hours after 
the temperature had reached the normal, i. e. T till the second day of 
convalescence; it then persisted dining 5 lays. In all 23 specimens 
of urine were examined in this case during the 6 days of fever, bnt 
with an entirely neg atre soli s regards the pies e d : e of albumin. 
An occasional hyaline or fine granular cast could be found in the 
majority of these specimens. We submit this case of experimental 
yellow fever as one of especial importance from the clinical stand- 
point, since the absence of albumin during the attack would have 
probably led to an error in diagnosis. How very ex rt>tional such 
- may be we have no means of knowing. 1 

It will be observed that the quantity of albumi n present in this 
series of c ases was very mode 1 is e s I ana II of Table II . 

These cases were the only 2 of the 16 thai were not placed in bed from 

' It is of interesc to note that this i . \ sfol inoculation and -while 

in quarantine, had an intermittent albumin a i 

~ ■ " 5.1 22 1-2 9 



130 YELLOW FEVER. 

the very beginning of the attack. In the remaining 14, all of whom 
were kept at absolute rest during the whole period of the fever, the 
amount of albumin was small in 6 and insignificant in 8. We are 
inclined to believe, therefore, that both the course of the fever, as 
well as the quantity of albumin, were favorably affected by the early 
enforced rest of our patients. 

In conclusion we desire to invite attention to 2 matters which we 
consider of considerable importance in connection with the possible 
importation and propagation of yellow fever. First, we believe that 
the facts herewith presented indicate that the period of incubation of 
yellow fever occasionally exceeds the quarantine period of 5 days, 
and that although exceptional this must not be left out of considera- 
tion. Secondly, that our observations emphasize anew the impor- 
tance of the recognition by the profession of mild and very mild cases 
of yellow fever. Guiteras x says : ' ' I can not insist too much upon 
the importance of the diagnosis of the first case of yellow fever m a 
locality." He adds: ' ' Undoubtedly the cause of the epidemic of yel- 
low fever is to be found in the introduction into a community of cases 
that are not suspected to be yellow fever." In the light of our inves- 
tigations, we feel constrained to remark that the failure to detect 
cases of mild yellow fever has been, we believe, the most important 
factor in the development of the theory of the propagation of this 
disease by fomites. 

i Report of United States Marine-Hospital Service, Vol. XXVII, 1897-1898, p. 300. 




DR. JESSE W. LAZEAR. 



Chapter 6. 

THE PREVENTION OF YELLOW FEVER. 1 

By Walter Reed, M. D., Surgeon, United States Army, and James Carroll, M. D., 
Contract Surgeon, United States Army. 

The prevention of yellow fever since its first importation into the 
United States in 1693, and especially during the latter half of the 
past century, has commanded, perhaps, more attention on the part 
of those who were concerned with matters pertaining to the public 
health than the* prevention of any of the other acute infections. 
This has not been occasioned by the fact that its total sickness and 
mortality have exceeded that of other acute infectious diseases, such 
as typhoid fever or croupous pneumonia, but because rather of the 
proximity of its source to our shores; the lack of knowledge of its 
specific agent; the consequent mystery surrounding its origin and 
propagation; the alarmingly rapid spread and course of this disease, 
when once it had obtained a foothold, and the high mortality with 
which its epidemics have generally been attended. Although the 
duration of its presence in our seaports was plainly limited by certain 
seasonal conditions, yet during its brief reign — July to October — its 
ravages were such as to completely paralyze both the social and com- 
mercial interests of a given city, and even of an entire section of our 
country. 

The interval between 1793 and 1888 is almost 100 years, but upon 
the appearance of yellow fever we observe no difference of behavior 
on the part of the inhabitants of Jackson, Miss., in 1888, from that 
shown by the citizens of Philadelphia in 1793, except that the terror 
of the former was greater and their flight from their homes more 
precipitate than in the case of the latter. 

The recurrence of succeeding epidemics has, therefore, served to 
increase rather than to lessen the public alarm. 

It would be difficult to determine with accuracy the loss of life 
occasioned by the 95 invasions of our territory by yellow fever during 
the past 208 years. We have endeavored to collect from the most 
available sources the mortality caused by this disease, but have been 
unable to obtain any reliable data for the earlier epidemics. If we 
confine ourselves to the epidemics which have occurred since 1793, 
we find that there have not been less than 100,000 deaths from this 
cause. The greatest sufferer has been the city of New Orleans, with 
41,348 deaths, followed by the city of Philadelphia, with 10,038 
deaths. The epidemics of 1855, 1873, 1878, and 1879 claimed 7,759 
victims in the city of Memphis, Tenn. From 1800 to 1876, Charleston 
lost 4,565 of its citizens by attacks of yellow fever. New York, 
during the earlier and later invasions of this disease, has had 3,454 
deaths, while the epidemic of 1855 in Norfolk, Va., caused over 2,000 

1 Read at the 29th annual meeting of the American Public Health Association, held in Buffalo, N. Y., 
Sept. 16-21, 1901. 

131 



132 YELLOW FEVEB. 

deaths. During our brief occupation of the island of Cuba (July, 
1898-December, 1900), with every precaution brought into exercise 
to ward off the disease, there have occurred among the officers and 
men of our Army 1,575 cases of yellow fever, with 231 deaths. 

If we reckon the average mortality at 20 per cent, there have not 
been less than 500,000 cases of yellow fever in the United States 
during the period from 1793 to 1900. 

Turning for a moment to other countries, we find that the great 
epidemic of 1800, in the province of Andalusia, Spain, caused 60,000 
deaths, and that 20,000 more deaths attended the invasion of the 
city of Barcelona by this disease in 1821. From 1851 to 1883, the 
deaths from this cause in the city of Rio de Janeiro were 23,338, 
while in the city of Habana, between the years 1853 and 1900, 35,952 
deaths have been recorded from yellow fever. 

We have no means of computing the damage done to the commercial 
interests of the United States by epidemics of yellow fever. At the 
sixth annual meeting of this association, held in Richmond, Va., in 
1878, Dr. Samuel Choppin, president of the State board of health of 
Louisiana, estimated the actual cost of the epidemic of that year to 
the material resources of the city of New Orleans as $ 1 0,752, 500 « 
Dr. Benjamin Lee, the present distinguished occupant of the presi- 
dential chair, at the seventeenth annual meeting of this association, 
held in Brooklyn, N. Y., in 1889, contributed a paper having the 
title, "Do the Sanitary Interests of the United States Demand the 
Annexation of Cuba?" From this we quote the following sentence: 
"A single widespread epidemic of yellow fever would cost the United 
States more in money, to say nothing of the grief and misery which 
it would entail, than the purchase money of Cuba." That this 
was no exaggeration, witness the language of the petition which the 
chairman of the committee on the etiology of yellow fever, in con- 
junction with other prominent members of this association, presented 
to the President of the United States on November 15, 1897, and 
again, on November 21, 1898, in accordance with a resolution adopted 
at the meeting of this association, held at Ottawa, Canada, in 1897. 
In addressing President McKinley, Dr. Horlbeck said: "It is hardly 
necessary to call your attention to the serious results of the recent 
epidemic of yellow fever in the States of Louisiana, Mississippi, and 
Alabama, but we may be permitted to mention the fact that the 
great epidemic of 1878 resulted in the loss of nearly 16,000 lives, and 
that it has been estimated that the total loss to the country resulting 
from this epidemic was not less than $100,000,000." 

The importance of the study of the causative factors entering into 
the propagation of a disease so capable of quickly destroying the lives 
of the citizens and wrecking the commercial interests of the cities 
of the United States could hardly be overestimated. Did time 
permit, we would be glad to refer to the numerous and valuable 
contributions made to this subject by the members of the American 
Health Association. We can only mention the establishment of the 
National Board of Health and the appointment of the Habana Yellow 
Fever Commission of 1879 as two or the most important outcomes of 
the persistent efforts of this association, following ' l the deeply tragical 
events of the summer of 1878." The exhaustive reports made by 
Chaille in 1880, and by Sternberg in 1890, must always stand as 
monuments to the earnest spirit of investigation with which the work 
was pursued. 



YELLOW FEVER. 133 

Notwithstanding the importance of the work and the efforts put 
forth by students in this and other countries, we believe that we are 
safe in saying that no results had been obtained which would enable 
us to combat successfully this disease when once imported into our 
larger centers of population, and no means found to keep it out of 
our ports except such as would place very heavy burdens upon com- 
merce. This inability to control the disease grew not only out of our 
ignorance as to the way or ways in which yellow fever was propagated, 
but also out of certain false opinions which we had formed as to the 
mode of its spread. The doctrine of the spread of yellow fever by 
fomites and by filth had taken such hold on the professional mind 
as completely to overshadow all other views, and to direct into false 
channels the work of those who were engaged in the investigation of 
this disease. The efforts to isolate or to discover the specific agent of 
yellow fever, if successful, would possibly have greatly simplified the 
problem; in the absence of such discovery, the first step in our knowl- 
edge of how to prevent this disease could only be found, we think, 
along another line, viz, that of its propagation from the sick to the 
well. This step we endeavored to take in connection with our col- 
leagues, Dr. Agramonte and the late Dr. J. TV. Lazear of the United 
States Army, during our recent investigations into the causation and 
spread of yellow fever at Quemados, Cuba. 

The results of our earlier work relative to the etiology and propa- 
gation of this disease we had the pleasure of presenting to this asso- 
ciation at its last meeting, held in Indianapolis, Ind. 1 You will recall 
that one of the conclusions which we then submitted was as follows: 
''The mosquito serves as the intermediate host for the parasite of 
yellow fever." In the same article, we briefly indicated the reasons 
which influenced us in pursuing this line of investigation, and it is, 
therefore, unnecessary here to repeat them. 

Continuing our studies, especially as regards the means by which 
yellow fever is spread from individual to individual, and as to the 
manner in which houses become infected, we were able, under strict 
rules of isolation and quarantine, to bring about an attack of yellow 
fever in 10 nonimmune individuals (and alwaj's within the period of 
incubation of this disease) out of a total of 13 (76.84 per cent) whom 
we attempted to infect by means of the bites of mosquitoes — Stegomyia 
fasciata — that had previously been fed with the blood of yellow-fever 
patients during the first, second, and third days of their attacks. 
These results were reported in part to the Pan-American Congress 
held in Habana during February of this year, 2 and in part to the 
Association of American Physicians at its last meeting, held in the city 
of Washington. 3 

It will be seen that we were able to establish in the most conclusive 
manner that the mosquito does serve as the intermediate host for 
the parasite of yellow fever. At this same experimental sanitary 
station we were also able to demonstrate that, an attack of yellow 
fever can not be induced by the most intimate and prolonged contact 
with the clothing and bedding of yellow-fever patients, even though 
these articles had been previously thoroughly and purposely soiled 
with the excreta of such patients. In other words, we were able to 

i "The Etiology of Yellow Fever— A Preliminary Note. " Philadelphia Medical Journal, Oct. 27, 1900. 
2 "The Etiology of Yellow Fever— An Additional Note. 7 ' Journal American Medical Association, 
Feb. 16, 1901. 
» •'Experimental Yellow Fever. " American Medicine, July, 1901. 



134 YELLOW FEVER. 

prove that the garments worn, and the bedding used, by yellow-fever 
patients were no more concerned in propagating this disease than the 
clothing and bedding of patients suffering from malarial fever are 
concerned in the spread of the latter malady. The doctrine of the 
spread of yellow fever by fomites having, at the first touch of actual 
experiment on human beings, burst like a bubble, we may hereafter 
cast it aside, with other exploded beliefs, to the very great simplifi- 
cation of the problem how to prevent yellow fever. Indeed, in our 
opinion, the time has now arrived when the latter problem may be 
reduced to measures which shall prevent the propagation of this dis- 
ease by mosquitoes. Although this specific agent of yellow fever has 
not, as yet, been discovered, this must remain largely a matter of 
scientific interest, and does not in the least lessen the efforts which 
we, as sanitarians, are now able for the first time to bring into action 
for the prevention of the spread of this disease, since in dealing with 
the mosquito we are dealing with the intermediate host which carries 
the specific agent from the sick to the well. 

In considering, then, in a broad way, the prevention of yellow fever, 
the natural order would be to give our attention, first, to measures 
which will prevent the importation of this disease from infected 
places into the seaports of the United States ; and secondly, to meas- 
ures which will most effectually prevent the spread of this disease, 
provided it should gain a lodgment in one of the cities of this country. 

With your permission, however, we will reverse the order of con- 
sideration above suggested, and will later refer in the briefest manner 
to the prevention of the importation of yellow fever into the United 
States from foreign ports, as this part of the subject will be presented 
by the health officer of the port of New York, who, from long expe- 
rience, will be able to deal more intelligently than we with this part 
of the problem. 

Since the mosquito, especially that species of stegomyia which has 
recently been designated by Theobald as Stegomyia fasciata (formerly 
known to entomologists as Culex fasciatus Fab.), has become so prom- 
inent a factor in the spread of yellow fever, it becomes necessary to 
consider this insect from the point of view of its identification; its 
habitat; its breeding places; the length of its generation; its hours 
of feeding; the influence of temperature upon both its propagation 
and stinging; the interval after contamination before the insect 
becomes capable of propagating the disease; the length of time during 
which it remains dangerous; the measures that should be used not 
only to protect the sick against the bites of these insects, but also to 
prevent the latter from infecting the healthy individual; and, finally, 
a consideration of the several agents which may be successfully 
employed both to prevent the breeding of mosquitoes as well as 
directed toward their destruction in the adult stage. 

Aside from the standpoint of scientific interest, it is certainly a 
matter of hygienic importance, in taking up the question of how to 
prevent the spread of yellow fever, when imported into the United 
States, that the health authorities of our several coast cities, and, 
indeed, of some of our inland towns, should be able to determine 
whether the only species of mosquito, which, up to the present time, 
has been shown capable of conveying yellow fever, is or is not present 
in these cities. If it should hereafter be proven that only species of 
the genus stegomyia are capable of acting as intermediate hosts for 



YELLOW FEVER. 135 

the specific agent of yellow fever, as appears to have been demon- 
strated for the geuus anopheles in the spread of malaria, the presence 
or absence of the former genus will definitely determine whether 
yellow fever will or will not spread in a given locality. The presence 
or absence of mosquitoes that can propagate the disease is the only 
intelligible explanation of what has heretofore been considered an 
inexplicable problem, viz, the capability of this disease to propagate 
itself in certain localities, while in other places it could be introduced 
with perfect impunity to the public health. In other words, our 
present knowledge of this question solves, at last, the problem of the 
portability or nonportability of yellow fever. 

Description of mosquito. — The identification of stegomyia fasciata, 
Theobald, should not be difficult. This mosquito, when examined 
closely with the naked eye and especially with a pocket lens, is a 
rather striking-looking and handsome insect. (Fig. 1.) Its most 
conspicuous markings are the broad semilunar silvery stripe, which 
is seen on the lateral surface of the thorax, and the white stripes at 
the bases of the tarsal joints. These may be readily distinguished 
with the naked eye. The bands on the hind legs are especially well 
marked, and occasionally the entire fifth hind tarsal joint is seen to 
be of a pure silvery white. The four stripes of silvery scales which 
are seen on the posterior surface of the thorax serve to distinguish 
this species from all other mosquitoes, except stegomyia signifer, 
Coquillet, in which, however, as we have been informed by Mr. L. O. 
Howard, the curved thoracic band is very narrow and of a somewhat 
different shape. Examined with a hand lens, the four stripes are 
seen to consist of two lateral, distinct silver lines — the continuation 
of the semilunar, broad stripes — and two fine, white lines situated 
between these, and which require that the insect shall be held in the 
proper light, in order that these delicate threads may be distinctly 
seen. The lateral surface of the thorax is also marked by several 
silvery dots and the abdomen by distinct white stripes. This de- 
scription applies to both sexes. In the female, the palpi are short, 
as in the genus culex. The proboscis is of a dark blackish-brown 
color and is destitute of a whitish band near the middle. In the 
male (fig. 2), one of the front tarsal claws bears a tooth on the under 
side, while the other claw is destitute of such marking. In the 
female, both front tarsal claws bear a distinct tooth near the base 
of the under side of each. 

Habitat. — We have found this mosquito in all of the principal cities 
of Cuba, and have received specimens from a number of the smaller 
towns on this island. According to Howard x it has been found at 
Kingston, Jamaica, on the Isle of Pines, and at Bluefields, Nicaragua. 
He also reports that Theobald has received specimens of this insect 
from Italy, Greece, Spain, Portugal, Gibraltar, and Malta. In the 
United States, Howard reports its presence at New Orleans, Natchi- 
tochez, and Napoleonville, La., ; in eastern Texas; Hot Springs, Ark. ; 
Pelham, Ga. ; and from Virginia Beach, near Norfolk, Va. To this 
we can add Augusta, Ga., from which city we have recently received 
specimens of stegomyia fasciata through the courtesy of Dr. T. O. 
Oertel of that city. Dr. Durham, of the English commission for the 
study of yellow fever, kindly showed us specimens of this insect which 

1 "Mosquitoes," etc., by L. O. Howard, New York, 1901. 



136 YELLOW FEVER. 

he had collected at Para, Brazil, and at various places along the 
Amazon River. It will be seen, therefore, that stegomyia fasciata has 
a wide distribution in the warmer countries of the globe, and espe- 
cially at low altitudes. A more exact knowledge of the distribution 
of this mosquito in the United States is, we think, a matter of con- 
siderable practical importance. 

Breeding places. — In our search for the larvse of this insect we have 
found them in the following places: (1) In rain-water barrels; (2) 
in sagging gutters containing rain water; . (3) in tin cans that had been 
used for removing excreta and which still contained a small amount of 
fecal matter; (4) in cesspools; (5) in tin cans placed about table legs 
to prevent the inroads of red ants; (6) in the collection of water at 
the base of the leaves of the agave americana; (7) in one end of a 




Fig. 1. — Stegomyia fasciata; female, a, Front tarsal claw. 

horse trough that was in daily use. It follows that stegomyia, like 
culex, will breed in any collection of still water, rain or hydrant, and 
that the presence of fecal matter does not seem objectionable. Indeed, 
we have been in the habit of adding a very small quantity of the latter 
to our breeding jars, as it has seemed to hasten the development 
of the larva?. In water, however, which contains much suspended 
soil— muddy water — the larvse, in our experience, do not flourish, 
but die off rather rapidly. 

Deposition of eggs. — The insect lays her eggs during the night, and, 
unlike culex, which deposits its eggs in boatlike masses, stegomyia 
extrudes her eggs on the surface of the water in pairs, in groups of 
three or more, or singly; in this respect resembling anopheles. 
(Fig. 3.) Exceptionally, the eggs are deposited in a rather close- 



YELLOW FEVER, 



137 



lying mass. (Fig. 4.) The whole batch is laid in one night, or 
extending over two or three nights. The number of eggs deposited 
varies from about 20 to about 75 — rarely a larger number. Sixteen 
careful counts gave an average of 47 eggs. At the same time that the 
female deposits her eggs, she frequently, but not always, discharges a 
fluid which forms a very thin film over the surface of the water, which 
possibly assists in floating the eggs. The latter are of a jet-black 
color and, to the naked eye, cylindrical in shape, one end of the egg 
being rounded and blunt, while the other is slightly pointed, the 
whole resembling closely a Conchita cigar. They measure about 
0.65 mm. in length by 0.17 mm. in width at the broadest part. Under 
a low power, the surface of the eggs is seen to be marked by tolerably 
regular six-sided plates, each of which is further marked in the center 




Fig. 2.— Stegomyia fasciata; male, a, Front tarsal claw. 

by a little round elevation, which gives to the surface of the egg a 
decidedly roughened appearance. (Fig. 5.) Under this low ampli- 
fication it is also seen that, while one side of the egg is somewhat con- 
vex, the other is flat or slightly concave and that a cross section of 
the egg would present the appearance of a triangle instead of that of 
a cylinder. This flattening of the surface of the egg does not appear 
to extend quite to the ends, which are round in shape. Although 
floating perfectly if left undisturbed, any agitation of the water, 
especially of a rough character, is apt to cause some or a majority 
of the eggs to sink. If by slight pressure the egg is pushed beneath 
the surface of the water it at once sinks and does not rise again. 
This sinking of the eggs does not interfere with their subsequent 
hatching, as in our experience submerged eggs furnish about as many 
larvae as those which are left floating on the surface. 



138 



YELLOW FEVER. 



fertility. 




Fig. 3.— Stegomyia fasciata. 
Batch of fifty-two eggs as de- 
posited by a single female. 
Slightly enlarged. 



The resistance of stegomyia' s eggs to external influences is worthy 
of note. Drying seems to be but little injurious to their subsequent 
We have found that eggs dried on filter paper, and kept 
for periods of from 1.0 to 90 days, will promptly 
hatch when again submerged in water. Dried 
eggs brought with us from Habana, in Feb- 
ruary, were easily hatched during the month 
of May in Washington, furnishing about 60 
per cent of the usual number of larvaB hatched 
from fresh eggs. Freezing does not destroy 
the fertility of the eggs ; although freezing with 
a mixture of salt and ice for 30 minutes has 
several times seemed to prevent subsequent 
hatching; on one occasion a batch of 155 eggs, 
freshly deposited, which were frozen at a tem- 
perature of — 17° C, for one hour, then thawed out at room tempera- 
ture and placed in the incubator at 35° C, began to hatch on the 
sixth day, the majority furnishing active larvae on the eighth day. 
In another observation, freshly deposited eggs, 
frozen at — 17° C. for half an hour on two succes- 
sive days, began to hatch on the third day as usual 
at incubator temperature. The resistance of ste- 
gomyia' s eggs to drying for a period of three 
months would appear to demonstrate that this 
genus of mosquito could survive the winter in 
Habana without the presence of hibernating 
females. Doubtless the genus is preserved in both 
ways. ' It is probable that the same could occur in 
our extreme southern latitudes. 

Length of generation. — The impregnated female, 
having obtained a meal of blood, proceeds to de- 
posit her eggs, in captivity, after an interval vary- 
ing in our experience from 2 to 30 days — as a rule, the eggs are laid 
within 7 days; sometimes a second or third meal of blood is taken 
before any eggs are laid. Eggs placed under favorable conditions of 

warmth — i. e., summer or incu- 
bator temperature — begin to 
hatch, as a rule, on the third 
day, the period extending to 
about 1 week. The larval stage 
requires 7 or 8 days, and the 
pupal stage about 2 days. The 
period for the generation may 
be stated, therefore, as follows: 
Incubation, 3 days ; larval stage, 
7 days; pupal, 2 days; total, 
12 days. As the eggs begin to 
hatch before the expiration of 
the third day, we generally ob- 
tain a few mosquitoes on the 
eleventh day. The shortest period of development observed by us dur- 
ing summer weather in Cuba was incubation, 2 days; larval stage, 6 
days; pupal, 36 hours; making the total length of this generation 9i 
days. This short period we believe to be quite exceptional. The 




Fig. 4.— Stegomyia fasci- 
ata. Forty -eight eggs 
deposited in a close- 
lying mass. Enlarged. 





Fig. 5.— Stegomyia fasciata. Newly deposited egg 
X 50. a, Empty shell from which larva has escaped. 



YELLOW FEVER. 



139 




Fig. 6.— Stegomyia fasci- 
ata. Full-grown larva 
enlarged. 



first fully developed insects begin to emerge on the eleventh or twelfth 
day, and the whole number have reached maturity by the fifteenth 
or eighteenth day after deposition of the eggs. The young larvae, in 
emerging, rupture the shell at a point about one-fifth the length of 
the egg from the larger end. This cap-like end can be frequently 
seen turned back and still adhering to the rest of the shell. (Fig. 5.) 
The larva and pupa of stegomyia (figs. 6 and 7) resemble fairly 
closely those of culex, and the larvse maintain the same relative 
position to the surface of the water; i. e., while in 
the act of breathing they assume a vertical posi- 
tion, with the head directed downward. 

Influence of temperature on 'propagation. — We 
have just seen that at summer temperatures the 
time required for a complete generation of this 
insect is from 11 to 18 da}'s. We may say that 
at an average temperature of 75° F., or over, 
stegomyia multiplies abundantly. Exposure to a 
cooler temperature, even for a short time daily, 
much retards the development of this mosquito. 
Thus, a batch of 51 eggs kept at 35° C, but which 
were placed in a cool chamber at 20° C. for two 
hours daily during the whole process of develop- 
ment, although furnishing a few larvae at the end 
of the third day, were not all hatched until the 
eleventh day. The first pupae appeared on the 
fourteenth day and the first mosquito -on the 
nineteenth day; the whole process being completed in 27 days, instead 
of the usual 15 to 18 days. The loss of insects was about 50 per cent. 
Eggs kept at a temperature of 20° C. (68° F.) do not hatch, in our 
experience. Newly hatched larvae kept at this temperature develop 
very slowly and require about 20 days to reach the pupal stage. Mos- 
quitoes developed under such conditions are feeble, and but few 
arrive at maturity. Young larvae kept at 10° C. (50° F.) have failed 
to reach the pupal stage, although some growth takes place. In one 
experiment more than 50 per cent were dead at the 
end of two weeks, and none survived the thirty-sec- 
ond day. Half-grown larvae and pupae exposed to a 
temperature of 20° C, and even as low as 10° C, con- 
tinue to develop slowly, but the few insects which 
escape drowning have, as a rule, been of feeble 
strength and have refused to bite. Although the 
reduction of the temperature to the freezing point, 
or below, would not necessarily destroy the vitality 
of the eggs of this genus of mosquito, it should be 
remembered that a reduction of temperature to 68° F., 
or below, for even a few hours of the 24 will much 
retard the development of the generation. At a temperature less than 
68° F. the eggs of this insect have ceased to hatch. 

Influence of temperature on biting. — While the nonimpregnated 
female does not appear to bite, the impregnated female is generally 
ready to bite on the second or third day of her existence; they very 
rarely suck blood on the first day. This species of mosquito, when 
not deprived of its liberty, although occasionally biting during the 
morning hours, has, in our experience, been especially active from 
the hour of 4 p. m. till midnight. In captivity, the hungry impreg- 




Fig. 7.— Stegomyif 
faseiata. Pupa, en 
larged. 



140 YELLOW FEVER. 

nated female will bite at any hour of the day or night. The meal of 
blood appears to have been thoroughly digested on the third day, 
when the insects, if applied to the surface of the skin, can be again 
readily induced to feed. When freed in a room, the female does not 
appear to bite a second time till about five, or even seven, days have 
elapsed. 

As regards the effect of temperature in the stinging of Stegomyia 
fasciata, the results of a number of observations made by us show 
that this mosquito will bite at temperatures of 62° F. and above. At 
temperatures below this point, we have not, as yet, succeeded in in- 
ducing even very hungry females to suck blood. We may, therefore, 
saythat observations thus far made appear to show that Stego- 
myia fasciata, while not breeding at temperatures below 68° F., will 
still bite at a temperature as low as 62° F., but probably not at lower 
temperatures. 

If this insect is concerned in the propagation of yellow fever, it is 
now quite apparent why an epidemic of this disease should fall to a 
low ebb in the city of New Orleans during the month of November, 
with a mean temperature of 61.8° F., and practically cease in Decem- 
ber, with a mean temperature of 55.3° F. A careful study of the 
charts herewith submitted (figs. 8 and 9), showing the monthly mean 
temperatures of the cities of Habana and New Orleans and Habana 
and Rio de Janeiro together with the relative monthly mortality from 
yellow fever in these cities, will prove of interest, we think, as show- 
ing better than laboratory observations the general effect of tempera- 
ture upon the breeding and biting of Stegomyia fasciata. In the light 
<of recent researches, we can now understand that while yellow fever 
can, and does, prevail during the entire year in Habana and Rio de 
Janeiro — although at a comparatively low ebb during the winter 
months — it can not propagate itself in New Orleans from December 
to May. 

Interval after contamination before the mosquito becomes dangerous. — 
In our experimental work on human beings, we have not succeeded 
in inducing an attack of yellow fever by the bites of mosquitoes which 
had been kept less than 12 days after contamination. The same 
insects which failed to convey the disease on the eleventh day were 
capable of so doing on the seventeenth day after infection. This inter- 
val of about 12 days, which appears necessary for the development 
of the parasite within the mosquito, plus the period of incubation, 
agrees with the time that has been observed to elapse between the 
introduction of an infecting case into a locality and the occurrence of 
the first secondary case, viz, two to three weeks. 

After the mosquito has once become dangerous, how long it remains 
capable of conveying the disease, although important, has not been 
determined. We have reported cases of yellow fever caused by the 
bites of stegomyia at intervals varying from 12 to 57 days after con- 
tamination. Here the dangerous interval was 45 days, but as one of these 
insects lived until the seventy-first day after biting a yellow-fever 
patient, the dangerous interval would here be prolonged to 59 days, or a 
little over 8 weeks. In our experience, the infected insect appears to 
live about as long as the noninfected mosquito, so that the answer to this 
.question would depend upon the length of life of the mosquito. This 
we do not know. While in captivity, the majority of mosquitoes do 



YELLOW FEVEK. 141 

not survive, with the best of care, more than about five weeks, and 
many die within half of this time ; we are ignorant as to the length of 
time during which they may live when under natural conditions. 
Certainly, during summer weather this will depend largely on the 
opportunity which the mosquito has of obtaining access to water. 

Measures to prevent the spread of the disease when imported. — A case 
of yellow fever having been imported into one of our seaport cities, 
we are now prepared to discuss the measures that should be taken 
to prevent its spread. The problem resolves itself into the simple 
one of excluding mosquitoes from access to the sick individual and 
of destroying those insects that have already become infected. We 
can leave out of consideration any danger from wearing apparel or 
baggage, which, in our opinion, may be dismissed as harmless. 

The fear that has been entertained that infected insects may be 
imported in boxes or trunks we believe to be absolutely groundless, 
and this for the simple reason, as shown by numerous observations 
made by us, that mosquitoes, when deprived of water, die within a 
few days. Even if allowed to fill themselves with blood immediately 
before the experiment is begun, and then deprived of water, practi- 
cally all are dead by the expiration of the fifth or commencement of 
the sixth day. We may say that of a large number of insects tried 
in this way only one female has survived until the sixth day, and 
then in a feeble condition. Males and females which have been living 
on sugar and water, or fed two days before on blood, if deprived of 
water and food, begin to die after 24 hours, and all are dead on the 
fourth morning. Free access to water, therefore, is necessary for the 
existence of this mosquito. 

Add to the deprivation of water the chances of injury to so frail 
an insect packed in with articles of clothing, etc., and we see that 
infected mosquitoes can not be imported alive in baggage that has 
been five days en route. 

As the first special measure of prevention, then, we should give 
our prompt attention to the protection of the sick individual against 
the bites of mosquitoes. This can best be accomplished by thorough 
screening, without delay, of the windows and doors of the room 
occupied by the patient and with as little disturbance as possible, so 
that any insects already present in the room may be prevented from 
escaping. As it will not be feasible to make use of any of the 
destructive agents against mosquitoes already within the patient's 
room until recovery, every precaution should be used to see that the 
insects do not escape in opening and closing the door. Screens at 
windows should not, for this reason, be movable. As it is possible 
that mosquitoes that have already bitten the sick individual may 
have escaped into other apartments of the house, these should be 
closed tightly and subjected either to sulphur or to formaldehyde 
disinfection or to the fumes of burning pyrethrum. According to 
Dr. Gorgas, the efficient health officer of Habana, preference is given 
to pyrethrum powder, burned in the proportion of 1 pound to 1,000 
cubic feet of air space. 1 He, however, adds: 

As the pyrethrum powder, even in this large quantity, does not certainly kill all 
mosquitoes, the room is opened at the end of three hours and the mosquitoes on the 
floor swept up and burned. 

i Medical Record, New York, vol. 60, No. 10, Sept. 7, 1901. 



142 



YELLOW FEVEE. 



We have mentioned above, in the order of their efficiency, the 
agents which are most destructive to stegomyia. According to our 



III • 



•jWwmw 



-. u&qo;D0 



- Amr 



- ftU(&> 



- ya#W' 



-A&?M2%r 



/ZimztPf 



•» s 





observations, an exposure for one and a half hours to sulphur fumi- 
gation, in a well-closed room, in the proportion of 1 pound to 1,000 



YELLOW FEVER. 143 

cubic feet of air space, will suffice effectually to destroy all mosquitoes. 
Formaldehyde gas is not quite so efficient. With Trenner's formal- 
dehyde generator, charged with formalin, 900 c. c; glycerin, 9 c. c; 
methyl alcohol, 360 c. c, which we have found quite reliable for the 
destruction of bacteria, an exposure of not less than three and pref- 
erably four hours is required in order to' kill these insects in a tight 
room having 2,800 cubic feet capacity. Pyrethrum powder, if 
burned in the proportion of 4 ounces to 1,000 cubic feet of air space, 
will stupefy all mosquitoes at the expiration of one hour, so that 
they will fall to the floor in a helpless condition. If used, however, 
the precaution above recommended by Dr. Gorgas should be strictly 
followed — that is, the room should be opened at the end of three 
hours and all insects carefully swept up and burned. The practice 
of destroying all mosquitoes in adjoining houses, as carried out in 
the city of Habana with such excellent results, we consider of the 
greatest importance, since only in this way can we hope to destroy 
infected mosquitoes, and thus prevent the occurrence of secondary 
cases. In other words, relying upon the well-known slow progress of 
the spread of yellow fever, we seek to catch and destroy all mosqui- 
toes within a given radius of the first case. If secondary cases should 
occur, the same hygienic measures should be rigorously enforced 
along the lines above indicated. Upon the completion of the case, 
the room occupied by the patient should be disinfected, and in a 
matter where so much is at stake we believe that sulphur should be 
given the preference as a disinfectant. In case of death, the body 
should be carefully screened against mosquitoes, as stegomyia will 
bite the dead body and might in this way acquire the parasite. 

We have said nothing about the protection of nonimmune individ- 
uals who enter the patient's room or house, since, if the case under 
consideration is the infecting case, no danger is incurred. As the 
duration of the attack is short, generally less than 10 days, the pa- 
tient's room will have been disinfected and the infected mosquitoes 
destroyed before they have become susceptible of conveying the dis- 
ease to others. We desire to emphasize the fact that the interval 
elapsing between the infection of this mosquito by biting a case of 
yellow fever and the time when it has become capable of conveying 
the disease, viz, about 12 days, is of the utmost importance in our 
efforts toward stamping out yellow fever at its very commencement, 
since it furnishes a nondangerous interval during which all infected 
insects should be easily destroyed. It thus makes the control of 
yellow fever hereafter a simpler and more certain matter than the 
suppression of an outbreak of any of the other acute infectious 
diseases. If nonimmunes entering an infected house desire protec- 
tion against the bites of stegomyia, this may be obtained by rubbing 
all exposed surfaces of the body, including the ankle surfaces, with 
spirits of camphor, oil of pennyroyal, or a 5 per cent menthol oint- 
ment. The protective effect of these substances is, however, only 
temporary. 

What we have already said concerning the breeding places of 
Stegomyia fasciata should sufficiently indicate the general hygienic 
measures that should be taken in order to prevent the spread of yellow 
fever. These should consist in enforcing such measures as will effec- 
tually destroy the breeding places of this very domestic mosquito. 



144 YELLOW FEVEB, 

The methods adopted by the chief sanitary officer of Habana, during 
the present year, may be taken as a model by our sanitary officials. 1 
It should not be forgotten that a well-drained and well-sewered city, 
with a pure water supply and clean streets, has no protection against 
the spread of yellow fever, provided rain-water barrels and other col- 
lections of water are present, in which stegomyia may breed. In one 
of the forts, on the outskirts of Habana, which was otherwise in an 
excellent sanitary condition, we found thousands of Stegomyia fasciata 
breeding in tin cans placed about the legs of a table in an officer's 
kitchen. Our conception of yellow fever, therefore, as a " filth" dis- 
ease must be abandoned, and our attention turned to yellow fever 
as a mosquito-borne disease. In illustration of what may be accom- 
plished by sanitation based on the latter method of propagation, we 
present herewith a chart (fig. 10) showing the actual monthly mor- 
tality from yellow fever in Habana, for the period from 1880 to 1899, 
and also for the years 1900 and 1901. Comparing the mortality from 
this disease for 1899, which was the most favorable year for yellow 
fever that Habana had experienced in 20 years, with 1901, during 
which sanitation, based on the demonstration that yellow fever is 
propagated by the mosquito, has been enforced, we find a reduction 
in mortality of 83.3 per cent in favor of the present epidemic year 
(Apr. 1 to Aug. 31); or if we compare the mortality for the epidemic 
year 1900 with the present year we observe a still greater reduction 
in favor of the latter, viz, 411 per cent. 

The sanitary regulations put into force February 15, 1901, by 
Dr. Gorgas, resulted in freeing Habana from yellow fever within 3 
months, so that for a period of 54 days — May 7 to July 1 — no case 
occurred. On the latter date, the disease was brought into Habana 
from Santiago de las Vegas, and, according to Gorgas, has been intro- 
duced into the city at least a dozen times from this and other sources. 
In spite of these new sources of infection, July has only furnished 
four cases, with one death, and August eight cases, with two deaths. 
If such admirable results, under new methods of sanitation, have been 
obtained in this hotbed of yellow fever, we can not believe that the 
intelligent and efficient boards of health of our cities will again permit 
this disease to assume an epidemic form in any city of the United 
States. 

Measures directed against the importation of yellow fever into the 
United States. — Under the admirable system of inspection and reports, 
as carried out by the Marine Hospital Service, the appearance of yel- 
low fever at any foreign port is promptly reported for the information 
of the health authorities of our several Atlantic ports. We may, 
therefore, divide foreign ports within the so-called epidemic zone 
into (a) infected, and (b) noninfected ports. Heretofore, no distinc- 
tion has been made by the health officers of our southern ports as 
regards quarantine regulations from April 1 to November 1, between 
infected and noninfected places. All ports within the epidemic zone 
of yellow fever were considered as being infected places, and hence pas- 
sengers and vessels were subjected to quarantine and to disinfection 
of both baggage and cargoes. 

With our present knowledge of the way in which yellow fever is 
propagated, we believe that in the treatment of passengers, as well 

i Medical Beeord„ Hew York, vol. 60, Sept. 7, 1901. 



YELLOW FEVER. 



145 



as of cargoes, a sharp distinction should be made, first, between 
infected and noninfected ports; and, secondly, in the case of vessels 
sailing from infected ports, between those that have received their 
cargoes and passengers in midstream and those that have loaded at 
the wharf. 




We believe that no quarantine restrictions should be placed upon 

either passengers or cargo from noninfected ports. In the case of a 

vessel loading in midstream at an infected port by means of lighters, 

we believe that she can only receive infection in one way, i. e., by 

79965°— S. Doc. 822, 61-3 10 



146 YELLOW FEVER. 

passengers who have been exposed to yellow fever on shore, and who, 
coming aboard, may thereafter be seized with the disease. The possi- 
bility of infected mosquitoes reaching the vessel, either by flight or 
by means of lighters, may be considered as highly improbable. 

Vessels, loaded under the foregoing circumstances (i.e., by lighters 
in midstream), and arriving at our ports without yellow fever devel- 
oped en route should have their nonimmune passengers quarantined 
for five days, counting the time consumed by the voyage as part of the 
quarantine period, and should be allowed to discharge their cargoes 
without delay. If the disease has developed en route among crew 
or passengers, the sick should be promptly removed; the forecastle 
or staterooms, as the case may be, thoroughly disinfected with sul- 
phur or formaldehyde gas, and the vessel allowed to proceed to her 
wharf. 

On the other hand, if the vessel has received her cargo at the wharf 
of an infected port, there is a possibility that she may have received 
infection in three ways: First, either by contaminated mosquitoes 
that have bitten a case of yellow fever in the immediate vicinity on 
shore; secondly, by mosquitoes that have become infected from bit- 
ing a yellow-fever patient present on another vessel loading at the 
same, or at an adjacent, wharf; or, thirdly, by some individual who 
has acquired the infection on shore and afterwards taken passage on 
the vessel. 

In our opinion, however, the chances of infection of a vessel by 
contaminated mosquitoes coming aboard from a house or ship in 
close proximity are very slight ; although such a possibility must be 
admitted, and the further possibility that recently infected mosquitoes 
may have sought refuge on the vessel during the night preceding her 
day of departure. It is also possible that a case of mild and hence 
undetected yellow fever may occur on board, and be the source for 
the infection of mosquitoes already present in the vessel. 

Under these circumstances, if a sufficient number of days have not 
elapsed between her port of departure and port of arrival in the United 
States, i. e., 16 to 21 days, to demonstrate the presence of infected 
mosquitoes by the occurrence of a case or cases of yellow fever en 
route, we know of no way of absolutely excluding the possibility of 
importation of the disease by such a vessel than by the detention of 
all nonimmune passengers for such number of days as will show their 
freedom from infection, and by careful disinfection of crew's and 
passengers' quarters. 

If more than 20 days have elapsed during the voyage, without the 
occurrence of yellow fever, we see no good reason why either passen- 
gers or vessel should be detained. 

We have said nothing about the disinfection of the vessel's cargo, 
for the reason that we do not consider this to be necessary. The only 
possible excuse for subjecting the cargo to disinfection would be the 
fear of the presence of infected mosquitoes in the vessel's hold, pro- 
vided she had loaded at the wharf of an infected port. In this 
instance, if the voyage has consumed fi.Ye or more days, all mosqui- 
toes contained in the hold will have died; for, as we have already 
pointed out, Stegomyia fasciata lives only a few days if deprived of 
water. We can not too strongly insist that the danger of importation 
of yellow fever into the United States lies, not in cargo or personal 



YELLOW FEVEK. 



147 




148 YELLOW FEVER. 

baggage, but in the individual sick with that disease. With our 
present knowledge of its propagation, personal baggage should no 
longer be subjected to disinfection, and, with our increased ability to 
prevent its spread by measures easy of application, instances should 
be few and exceptional when a vessel coming from a yellow-fever port 
should be delayed longer than will be necessary to remove her non- 
immune passengers who have not yet completed their period of ^.Ye 
days since leaving the port of departure. 

The chief duty of quarantine officers hereafter will consist in the 
detection of mild or very mild cases of yellow fever. In a series of 
12 cases of experimental yellow fever produced by the bite of Stegomyia 
fasciata, we have, elsewhere, 1 pointed out that 4, or 33 per cent, 
were mild or very mild in character, and have indicated the difficulty 
of making a positive diagnosis in such cases. 

In discussing the period of incubation of experimental yellow fever, 
we have shown that in 16.6 per cent of our cases the period of incu- 
bation exceeded the usual quarantine period of fire days. If we add 
Carter's cases to those observed by ourselves, we find that of 24 cases 
the period of incubation exceeded five days in 3, or 12.5 per cent. 

We can thus readily see what great danger heretofore lay in the 
passage through quarantine of just such mild cases, or of those having 
an incubation stage of more than five days. 

While the exclusion of such cases is of the greatest importance, we 
doubt whether, with our improved knowledge of how to prevent the 
spread of yellow fever, it would be advisable to place a greater burden 
upon ships' passengers by extending the quarantine period to more 
than five days. It appears to us rather that in view of the trouble- 
some delays to which passengers and vessels from yellow-fever ports 
have been subjected in the past, the time has now arrived when, 
standing upon more solid ground, we will be justified in seeking in 
every way to lessen as much as possible the restrictions placed by 
present quarantine regulations upon the ship's cargo, while we add 
nothing to those of the passenger. 

To this end a most important part will have been accomplished if 
we can persuade the sanitary authorities of our sister republic, Mexico, 
and of the Central and South American States, to join us in the adop- 
tion of more enlightened methods for the suppression of this widely 
prevalent epidemic. 

1 "Experimental Yellow Fever." Transactions of the Association of American Physicians, Vol. 
XVI, 1901. 



Chapter 7. 

THE ETIOLOGY OF YELLOW FEVER— A SUPPLEMENTAL NOTE. 1 

By Walter Reed, M. D., Surgeon, United States Army, and James Carroll, M. D., 
Contract Surgeon, United States Army, of Washington, D. C. 

Informer contributions to this subject, we have shown by observa- 
tions made on human beings that yellow fever may be produced in 
the nonimmune individual either by the bite of the mosquito (1) (genus 
Stegomyia) that has previously been permitted to fill itself with the 
blood of a patient suffering with yellow fever, during the first three 
days of the attack, or by the subcutaneous injection of a small quan- 
tity of blood (2) (0.5 to 2 c. c.) drawn from the general circulation 
of such a patient during the active stage of this disease. For further 
particulars regarding these observations the reader is referred to the 
original papers. 

Although these experiments have demonstrated that the specific 
agent of yellow fever is present in the blood, we may say that the 
prolonged microscopic search which has been made by other investi- 
gators, as well as by ourselves, both with fresh and stained prepara- 
tions of blood, taken at various stages of this disease and during early 
convalescence, has proved thus far entirely negative. We may 
add that the efforts which we have made with reasonable hope of 
reward, both in the bodies of infected mosquitoes, dissected in the 
fresh state, as well as by serial sections of the hardened insect, have 
likewise given no results which we consider worthy of record at the 
present time. Leaving out of consideration, therefore, for the time 
being, the further microscopic search for the specific agent in the 
blood of the sick and in the bodies of infected mosquitoes, we desire 
to call attention to some additional observations bearing on the 
etiology of the disease, which one of us (Carroll) has recently made 
at Las Animas Hospital, Habana, Cuba, and at Columbia Barracks, 
near Quemados, Cuba. 

We here desire to express our sincere thanks to Dr. William H. Welch, 
of the Johns Hopkins University, who, during the past summer, 
kindly called our attention to the important observations which have 
been carried out in late years by Loeffler and Frosch relative to the 
etiology and prevention of foot-and-mouth disease in cattle. In the 
course of their investigations concerning a reliable method of immu- 
nization in this disease, the authors had occasion to dilute and after- 
wards to pass several times through a porcelain filter, lymph which 
had been collected from the blebs present in the mouth and on the 
feet of cattle sick with foot-and-mouth disease (4). 

These observers, having already ascertained that immunity could 
be conferred upon cattle by the subcutaneous or intravenous injec- 
tion of one -fortieth to one-fiftieth c. c. of pure lymph previously 

i Read before the third annual meeting of the Society of American Bacteriologists, Chicago, 111., Dec. 31, 
1901, and Jan. 1, 1902. 

149 



150 YELLOW FEVEE. 

mixed with 1 c. c. of the defibrinated blood of an animal that had 
recently recovered from the disease, desired to find out whether the 
injection into calves of given quantities of this filtered and bacteria- 
free lymph would not, also, enable them to confer immunity of, 
perhaps, a higher degree upon cattle. 

The results were quite surprising, since it was shown that calves 
which had received one-tenth to one-fortieth c. c. of the diluted and 
filtered lymph developed foot-and-mouth disease just as promptly 
as calves that had been injected with corresponding quantities of the 
unaltered lymph. 

According to Loeffler and Frosch, there were two possible explana- 
tions of this remarkable result; either that the filtered lymph held in 
solution an extraordinary active toxin, or that the specific agent of 
the disease was so minute as to pass through the pores of a filter 
which prevents the passage of the smallest known bacteria. 

The authors accept the latter explanation, since they were able, 
in later experiments (4) , by means of the filtered lymph, to convey the 
disease through a series of six animals, the last of which sickened 
just as promptly after the injection of the filtered lymph as the first 
of the series. 

Having, therefore, conclusively determined that the microorganism 
of foot-and-mouth disease of cattle is so extremely minute as to pass 
readily through a porcelain filter, it was natural that LoefHer and 
Frosch should have put forward the suggestion that, perhaps, the 
specific agent of some of the acute infectious diseases of man and 
animals, such as smallpox, scarlet fever, measles, rinderpest, etc., 
might also belong to this group of ultramicroscopic organisms. 

It was for the purpose of ascertaining whether observations con- 
ducted along the same lines as those above mentioned might throw 
additional light upon the etiology of yellow fever that the following 
experiments were undertaken. 

Of course it will be thoroughly appreciated that in experimentation 
on human beings, aside from the grave sense of responsibility, at 
times well-nigh insupportable, which the conscientious observer must 
always feel, even with the full consent of the subjects to be experi- 
mented upon, there must be added another factor, viz, the difficulty 
of finding willing and suitable nonimmune individuals for experimen- 
tation just at the proper and urgent moment. It so happened that 
on the day of Dr. Carroll's arrival at Habana, August 11, 1901, the first 
patient of the series of seven cases of yellow fever which Dr. Guiteras (5) 
had produced by bites of infected mosquitoes, was taken sick. The 
fatal termination of three of these cases produced a somewhat panicky 
feeling toward experimental yellow fever among the nonimmunes at 
Habana, which feeling was intensified by the sensational and distorted 
statements in one of the local Spanish papers. It was, therefore, 
extremely difficult — in fact, practically impossible — to obtain for 
inoculation purposes persons who could with reasonable certainty be 
regarded as nonimmunes. 

Further, as it was not practicable to withdraw blood from any case 
of yellow fever under treatment in the city of Habana, it became 
necessary to produce cases by means of the bites of infected mos- 
quitoes — Stegomyia fasciata — accepting such subjects as were willing 
to submit to this mode of inoculation. In all six individuals, sup- 
posedly nonimmunes, were bitten by mosquitoes, of whom four gave 
a negative and two a positive result. 



YELLOW FEVER. 151 

The following are the negative cases: 

August 14, 1901. — S. V., Spaniard, resident of Habana for a few months, was bitten 
by two insects that had been applied to a yellow fever patient 34 days previously. 
Result negative, although the bites of two mosquitoes from this same lot had already 
infected an individual, who later died of yellow fever. 

September 5, 1901. — J. T., American, was bitten by nine insects that had been ap- 
plied to a mild case of yellow fever on the second day of the attack, 23 days before. 
He was again bitten 30 days later by four mosquitoes that had been applied to a mod- 
erately severe case of experimental yellow fever 11 days before. The result of both 
inoculations were negative. This man had resided one year in Central America, and 
we were afterwards informed that he had confessed to a previous attack of the disease. 

September 11, 1901. — A. P., Spaniard, was bitten by three insects which 53 days 
previously had bitten patient with a typical case, on the third day of the attack. 
These were among a lot of mosquitoes that had already infected three individuals, 
two of whom died of yellow fever. The result was negative. Five weeks later he 
received a subcutaneous injection of about one-fourth c. c. of blood drawn from a 
patient with a mild case of yellow fever, on the second day of illness . Result negative . 
The previous history of this man was not satisfactory, as he had recently returned from 
a residence in Mexico. 

September 9, 1901. — A. V., Spaniard, was bitten by three mosquitoes that had been 
applied to a mild case of yellow fever on the second day of the attack, 27 days before. 
Three weeks later he was again bitten by one mosquito 49 days after it had been ap- 
plied to a fatal case of yellow fever, on the third day of the' attack. The result of 
both inoculations was negative. 

We give brief sketches of the two positive cases: 

Case I. — P. R. C, a Spaniard, had served in the Spanish army in the Philippines. 
He arrived in Habana from Spain about August 30. 

On September 16, 1901, he was bitten at 4 p. m. by 4 mosquitoes that had previ- 
ously fed upon cases of yellow fever as follows: One had bitten a patient having a 
fatal case, on the third day of the disease. 53 days before, and 3 had bitten a patient 
having a fatal case, on the second day of illness, 34 days previously. His attack 
began at 4.30 p. m.. September 19, after an incubation period of 72£ hours. At the 
onset he experienced a slight chill with rigors and loss of appetite. Later in the 
evening he complained of slight frontal headache and pains in the lumbar region. 
On the following day the headache and backache were more severe. At 10 a. m. he 
vomited about 6 drams of slightly greenish fluid containing mucus. On the second 
day of the attack the gums were swollen, pale, and spongy, and there was soreness 
upon deep pressure over the epigastric and hypogastric regions; the face was flushed 
and the eyeballs were slightly yellow. September 24, fifth day, he was well jaun- 
diced, epigastric and abdominal soreness were pronounced, and there was nausea 
with eructations. At this time an unfavorable prognosis was given by two physi- 
cians of large experience in yellow fever. Happily, with the decline of temperature 
on the sixth day, the symptoms were much ameliorated and the patient made an un- 
interrupted recovery. Albumin appeared in the urine on the third day and persisted 
for 17 days. The microscope showed the presence of bile-stained epithelial and 
granular casts on the third and subsequent days. 

Early on the second day blood was drawn from the median-basilic vein with all 
precaution and 10 drops were immediately added to each of four flasks containing 
200 c. c. of sterile nutritive bouillon. The flasks were kept under observation in the 
incubator and at room temperature for 14 days without the development of any growth. 
At the end of that time each flask was agitated and an agar slant was freely inoculated 
with fibrin and fluid from its contents. These cultures remained sterile 16 days 
later after being kept four days in the incubator and 12 at room temperature. 

On the second day, blood was drawn for the purpose of obtaining serum for filtration, 
but owing to an accident to the vacuum pump the experiment had to be abandoned. 

Specimens of the fresh blood were examined for malarial parasites, with negative 
results, on the second and fourth days of the attack. (Chart I.) 

Case II. — J. M. A., Spaniard, recently landed at Havana, was bitten at 4 p. m. 
October 9, by 8 mosquitoes that had been applied to a severe case of yellow fever 
(Case I) on the second day of the disease, 18 days previously. The attack which fol- 
lowed was mild. According to his own account, he went to bed on the evening of 
the 12th feeling in perfect health. He awakened about midnight with frontal 
headache, but had no chill. October 13, 7 a. m. , temperature was 102.2° F., pulse 
92; complained of pain in the head and back; later in the day there was marked 
photophobia, pain in the region of the kidneys, and slight pains in the lower extremi- 



152 



YELLOW FEVER. 





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YELLOW FEVER. 153 

ties. The eyes were injected moderately and the gums slightly so. On the follow- 
ing day, October 14, the frontal headache was more severe, there was considerable 
soreness on pressure over the stomach and abdomen, and he complained of sharp 
lumbar pain. An examination of the fresh blood proved negative for malarial para- 
sites. At 4 p. m. blood was drawn from a vein at the bend of the elbow and 10 drops 
were inoculated into each of 2 flasks containing 200 c. c. of sterile bouillon. One 
flask remained sterile, the other developed a growth which proved to be a white 
staphylococcus. 

October 15 the gums were pale, swollen and spongy, their margins distinctly red- 
dened, and blood could be easily pressed out from beneath the lower gums. 

October 16 there was free oozing of blood from the gums and margin of the tongue. 
The case pursued a mild course, the temperature falling to normal at 9 p. m. of the 
fourth day. A trace of albumin was present in the urine passed on the morning of that 
day, and for a few days following hyalin and granular casts were found. The patient 
made a speedy recovery. (Chart II.) 

On October 15, 11.30 a. m., at the beginning of the third day of illness, the tempera- 
ture was 101° F.; 65 c. c. of blood were drawn, with antiseptic precautions, from a vein 
at the bend of the elbow. This was placed in a sterile test tube and set aside in the 
refrigerator. At 6 a. m., 5§ hours later, 19 c. c. of a slightly bloodstained serum were 
pipetted off into another sterile tube. After the addition of an equal quantity of 
sterilized distilled water the diluted serum was slowly filtered through a new Berke- 
feld laboratory filter that had been subjected to previous sterilization in an Arnold's 
sterilizer. In this way 35 c. c. of a slightly bloodstained filtrate were obtained, a part 
of which was subsequently used for the inoculation of Cases VII. VII, and IX of this 
report. 

The original level of the blood having been marked upon the tube into which it 
was drawn, a sufficient quantity of sterilized distilled water was then added to replace 
the 19 c. c. of serum that had been pipetted off and to make up the original volume of 
blood. The whole, consisting of clot, remaining serum, and distilled water, was 
poured into a sterile vessel and whipped up with a sterilized egg beater. The mix- 
ture, which approximately represented the partially defibrinated blood, was then 
divided into two parts, one of which was reserved for the inoculation of a control sub- 
ject (Case III), while the other part was placed in a double water bath previously 
heated, and exposed to a temperature of 55° C. for 10 minutes. It was then remo ved 
and immediately cooled in ice water. This cooled material was subsequently used for 
the injection of Cases IV, V, and VI. 

It will thus be seen that we have at our disposal, for purposes of 
inoculation, three kinds of materials, derived from the blood in Case 
II, viz: (a) The unheated and partially defibrinated blood: (jb) the 
partially defibrinated blood which had been heated to a temperature 
of 55° C. for 10 minutes, and (c) the diluted blood serum which had 
been filtered through a Berkefeld filter. Each of these materials 
was used for the inoculation of one or more nonimmune individuals 
with the results that follow herewith. 

(a) THE UNHEATED AND PARTIALLY DEFIBRINATED BLOOD. 

Case III. — M. G. M., Spaniard, arrived at Habana October 4, 1901. At 4 p. m. 
October 15 he was given a subcutaneous injection of 0.75 c. c. of the unheated and 
partially defibrinated blood obtained from Case II, 15 \ hours previously, which had 
been kept bh hours in the refrigerator and 10 hours at room temperature. The earliest 
symptom, frontal headache, was complained of at 6 p. m., October 20, or at the expi- 
ration of 5 days and 2 hours after inoculation. Temperature 100.6° F., pulse 80. At 
3 p. m. of the same day the temperature was 98.4° F., pulse 80. At that time the 
patient did not complain of any discomfort and there was nothing to indicate that he 
was about to be taken sick. October 21, 5 p. m., nearly 24 hours from the onset, there 
was flushing of the face, injection of the eyes and gums, and moderately severe head- 
ache; pain m the back, and tenderness on pressure in the epigastric region made the 
picture complete. On the third day the face was deeply flushed, eyes congested 
and distinctly yellow. There was slight oozing of blood from the gums. The urine 
passed at 7.30 p. m. contained a distinct trace of albumin. The case was seen by the 
Habana Board of Yellow Fever Experts and the diagnosis confirmed. The patient 
passed through a mild but typical attack, the temperature touchino: normal on the 
fifth dav. f Chart III.) 



154 



YELLOW FEVER. 



This case, therefore, serves as a ''control" for the observations 
which are to follow, since it demonstrates that the blood drawn from 
the general circulation of case II, at the beginning of the third day, 
contained the specific agent of yellow fever, and, in this respect, con- 
firms the observations which have heretofore been reported by us (6). 



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(&) THE PARTIALLY DEFIBRINATED BLOOD HEATED FOR 10 MINUTES 

AT 55° C. 



Case IV. — A. C, Spaniard, nonimmune, arrived at Habana, October 6, 1901. At 
4.35 p. m., October 15, he was given subcutaneously 1.5 c. c. of the partially defibri- 
nated blood which had been subjected to a temperature of 55° C. during 10 minutes. 
The specimen had been drawn from case II, 16 hours before. The result of this injec- 
tion was entirely negative, as the subject remained in perfect health during the 10 days 
following. 



YELLOW FEVEK. 



155 



Case V. — B. F. M., Spaniard, nonimmune, arrived at Habana, October 6, 1901. 
At 4.45 p. m., October 15, he received a subcutaneous injection of 1.5 c. c. of the same 
material that was used in case IV. Result negative. 

Case VI. — S. O., Spaniard, nonimmune, arrived at Habana, October 7, 1901. At 
4.50 p. m., October 15, he was given a subcutaneous injection of 1.5 c. c. of the same 
material that was used in cases IV and V. Xo rise of temperature or other symptoms 
of ill health followed this injection. 



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We desire to invite attention to the fact that the four subjects whose 
protocols have been given above were young Spaniards who arrived 
at Habana at a time when yellow fever was not present in die city ; 
that they were carried from the quarantine camp, at Triscornia, across 
the bay, direct to Columbia Barracks, near Quemados, Cuba, where 
they were kept for seven full days prior to inoculation; and that after 



156 YELLOW FEVER . 

inoculation they were kept under close daily observation for the 
further period of 10 days, during which time both temperature and 
pulse were recorded every third hour. Since under these circum- 
stances each of the three nonimmunes (cases IV, V, and VI) received, 
without any disturbance to health, double the quantity of heated and 
partially defibrinated blood that sufficed when unheated to cause an 
attack of yellow fever in case III, it follows that the specific agent 
present in the blood in yellow fever is destroyed, or, at least markedly 
attenuated, by a temperature of 55° C. maintained for 10 minutes. 

(c) THE DILUTED AND FILTERED SERUM. 

Case VII. — P. H., American soldier, nonimmune, received at 11 a. m. October 15, 
1901, a subcutaneous injection of 3 c. c. of the serum nitrate, representing 1.5 c. c. of the 
undiluted serum 10| hours after the blood had been drawn from Case II. He remained 
in good health until 3p.m. October 19, an interval of four days and four hours, when 
his face appeared flushed and his eyes somewhat injected. His temperature at this 
time was 101° F. , his pulse 80. He did not complain of headache or other pain. From 
this hour his temperature declined, until at 12 o'clock midnight it registered 98° F., 
pulse 72. October 20, 9 a. m., temperature 100.8° F., pulse 78. Face more suffused 
and slight headache complained of. Fever continued on the 21st, with more marked 
flushing of the face and injection of the eyes. The height of the primary febrile parox- 
ysm was reached at 6 p. m. October 21. Remission occurred at 9 a. m. October 22, 
when the temperature dropped to 98.8° F., pulse 64. This lasted for 24 hours and 
was followed by a secondary febrile paroxysm of 42 hours' duration. On the 23d 
blood was oozing from the lower gums and the eyeballs were tinged with yellow. 
Albumin appeared in the urine on the fourth day. The patient was visited by the 
board of experts and the diagnosis of yellow fever confirmed. Examination of the 
dried blood for malarial parasites was negative. The patient recovered. (Chart IV.) 

Case VIII. — A. W. C, American soldier, nonimmune, was also given at 11.05 a. m. 
October 15, 1901, a subcutaneous injection of 3 c. c. of the diluted and filtered serum, 
being the equivalent of 1.5 c. c. of the undiluted serum, 10J hours after the blood had 
been drawn. He remained in his usual health until about noon, October 19, at which 
time he felt "out of sorts ' ' and ate but little dinner. This was 4 days and 1 hour after 
the injection. During the afternoon he lay down and slept until 3 p. m., when he 
awoke with a severe headache and backache. His face was flushed. Temperature 
103.6° F. , pulse 102. At this hour his face and eyes were deeply congested, and from 
this time his symptoms were characteristic of the disease. On the 23d his eyes were 
quite yellow and general jaundice followed later. No albumin was found in this 
patient's urine. He was seen by the board of experts and his illness pronounced a 
typical case of yellow fever. Careful examination of the dried blood for malarial 
parasites was negative. The patient made a good recovery. (Chart V.) 

Case IX. — J. R. B., American, nonimmune, at 2.30 p. m. October 15, 1901, was 
given a subcutaneous injection of 3 c. c. of the diluted and filtered serum, equal to 
1.5 c. c. of the undiluted serum. Fourteen hours had elapsed since the blood had 
been drawn from Case II. 

This injection was followed by no symptoms of physical disturbance, until 3 p. m. 
October 19, an interval of four days and a half hour, when his temperature was 99.4° F. , 
pulse 92. He complained of headache and flashes of heat, with slight pain between 
the shoulders, symptoms which, the subject stated, were quite unusual to him. At 9 
p. m. temperature 98.4° F., pulse 84. There was no further febrile disturbance and 
the day following the subject was in his usual good health. 

We thus observe that of 3 nonimmune individuals who received 
subcutaneously an injection of filtered blood serum derived from 
case II of this report, 2 developed an unmistakable attack of yellow 
fever, after a period of incubation of 98 J hours and 100 hours respec- 
tively, while in 1 case the result must be regarded as negative. 

As already stated, the serum used for these inoculations had been 
slowly filtered through a new Berkefeld laboratory filter. As soon 
as possible thereafter the filter was resterilized by steam and thor- 
oughly tested as to its effectiveness in preventing the passage of 
bacteria. For this purpose a recent bouillon culture of Staphylococcus 



YELLOW FEVER. 



157 



pyogenes aureus was used, of which 50 c. c. were passed through the 
filter. The filtrate thus obtained was transferred in quantities of 
10 c. c. to each of two flasks containing 200 c. c. of sterile bouillon, which 
were incubated at 37° C. for 4 days and thereafter kept at room 
temperature for 10 days longer, at the end of which time no growth 
had occurred. It appears, therefore, that the filter used for the 
filtration of the blood serum in case II was to be relied upon for 
the delivery of a bacteria-free filtrate. 

The production of yellow fever by the injection of blood serum 
that had previously been passed through a filter capable of removing 
all test of bacteria, is, we think, a matter of extreme interest and 
importance. The occurrence of the disease under such circumstances, 
and within the usual period of incubation, might be explained in 
one of two ways, viz, first, upon the supposition that the serum 
filtrate contains a toxin of considerable potency; or, secondly, that 



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Chart IV.— Yellow fever, produced by Injection of 1.5 cc. of filtered blood-serum. Incubation, 4 days, 

4 hours. 



the specific agent of yellow fever is of such minute size as to pass 
readily through the pores of a Berkefeld filter. 

In favor of the supposition that in yellow fever an active toxin is 
present in the blood may be cited the early and well-marked jaun- 
dice; the free hemorrhage from the mucous membranes of the 
mouth and stomach, doubtless due to profound changes in capillary 
vessel walls; the rapid progress of the disease to a fatal termination, 
the advanced fatty degeneration of the hepatic cells, as well as the 
marked parenchymatous changes found in the kidneys. If present 
in the blood this toxin would in all likelihood be found in the serum 
filtrate obtained from the blood, and if injected in sufficient quantity 
might induce an attack of yellow fever in a susceptible individual 
after the usual period of incubation. In this respect it would bear 
analogy to the production of. tetanus in the human being, after the 
usual period of incubation of this disease by the subcutaneous 
injection of a very small quantity of tetanus toxin, as reported 
by Nicolas (7) in 1893, and more recently by Bolton, Fiscn, and 
Walden (8). 



158 



YELLOW FEVEK. 



Against the view that a toxin is present in the serum filtrate, we 
invite attention to the innocuousness of the partially defibrinated 
blood when heated to 55° C. for 10 minutes, as shown by the negative 
results in cases IV, V, and VI. Here the toxin, which must have 
been present in just the same quantity as in the serum filtrate obtained 
from this blood, appears to have been completely destroyed by the 
temperature above mentioned. Now, although certain bacteria are 
destroyed by this temperature, as yet we know of no bacterial toxin 
that is rendered inert by such a low degree of heat continued for so 
short a time. The tetanus toxin, which has been found to be the 
most sensitive thus far requires, according to Kitasato, a tempera- 
ture of 60° C. for 20 minutes, or 55° C. for 1 \ hours, in order to destroy 
its activity. (9) 

As a further test and in order to determine whether the serum 
filtrate contained something more particulate than a soluble toxin, 



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Chart V.— Yellow fever, produced by injection of 1.5 cc. of filtered blood serum. 

1 hour. 



Incubation, 4 days, 



we availed ourselves of the opportunity of observing the effect that 
would follow the transference to a third individual of blood drawn 
from one of the patients whose attack had been occasioned by the 
injection of 1.5 c. c. of serum nitrate (case VII). If under these 
circumstances it would be found that the injection of a small quantity 
of blood was followed by an attack of yellow fever in a third indi- 
vidual, the evidence would point in the strongest manner to the 
presence of the specific agent of the disease in such blood, since we 
can hardly believe that a toxin which had undergone so great a 
dilution in the body of the second individual would still be capable 
of producing the disease. 

Case X. — October 22, 1901, 3 p. m., J. M. B., American, nonimmune, who on 
October 15, 1901, at 2.30 p. m., had been injected with 1.5 c. c. of serum nitrate with 
negative result (vide case IX), and who still desired to have his immunity further 
tested, was, at the beginning of this, the eighth day after his former inoculation, given 



YELLOW FEVER. 



159 



a subcutaneous injection of 1.5 c. c. of blood drawn from the venous circulation of 
case VII early in the fourth day of the disease. At the time of inoculation the subjects' 
condition was quite normal. October 23, 3 p. m., after an incubation period of just 
24 hours, he complained of frontal and slight basal headache and some pain between 
the shoulders. His temperature was 99.6° F. and pulse 100. At 6 p. m., temperature 
100.4°, pulse 100. Pain in the back quite severe. At 10.15 p. m., he suffered a slight 
chill. On the following morning the face was flushed and the eyes and gums injected ; 
there was sharp frontal headache and some photophobia. The height of the primary 
paroxysm was reached at the end of 23 hours. Remission occurred at 9 a.m., October 
25, and was followed by a second febrile paroxysm of 45 hours' duration. On the 
third day, during the secondary fever, the patient presented the typical picture of a 
mild case of yellow fever; the face was deeply flushed, eyes well injected and slightly 
yellow; there was sharp headache, and epigastric tenderness and pain in the lower 
extremities. Heller's test showed albumin in the urine drawn on the fourth day. 
His fever subsided on the later day and he made a prompt recovery. The case was 
seen by the board of experts and the diagnosis confirmed. (Chart VI.) 

In considering this individual's attack, his infection must be 
attributed either to the injection of the serum filtrate derived from 
case II, in which event the onset of his disease was postponed until the 
commencement of the ninth day after inoculation, or to the injection 



Month. OCTOBER. 


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Chart IV.— Yellow fever, produced by injection of 1.5 cc. of blood. Incubation, 24 hours. 

of blood obtained from case VII, after a period of incubation of 24 
hours. 

In ourown experience (10) and that of Guiteras (11) of 22 cases 
of experimental yellow fever, following the bite of the mosquito, 
in which the period of incubation was definitely and accurately 
ascertained, the longest period was 6 days and 1 hour, and the shortest 
period 2 days and 13 hours. If we take the cases produced by the 
injection of blood, 7 in number, exclusive of the case under considera- 
tion, the longest period was 5 days and 2 hours (case III of this 
report) and the shortest 41 hours. 

In view of these data, we believe we are justified in expressing 
the opinion that the source of infection in case X must be attributed 
to the injection of blood drawn from case VII, rather than to the 
injection of the filtered serum derived from the blood in case II; and 
further, that the blood in case VII contained the specific agent of 
yellow fever, which had, therefore, passed through the filter along 
with the filtrate with which this latter individual had been inoculated. 

The important questions which naturally arise from the foregoing 
experiments must be left for the future observations to determine. 



160 YELLOW FEVER. 

BIBLIOGRAPHY. 

(1) The Etiology of yellow Fever — An Additional Note. Journal American Medical 
Association, February 16, 1901. 

(2) Experimental Yellow Fever. Transactions of the Association of American 
Physicians. Vol. xvi, 1901. 

(3) Berichte der Kommission zur Erforschung der Maul-und Klauenseuche bei 
dem Institut fur Infectionskrankheiten in Berlin. Centralblatt fur Bacteriologie, etc., 
Band xxiii, No. 9-10, p. 371^391. 

(4) Berichte der Kommission zur Erforschung der Maul-und Klauenseuche, etc. 
Centralblatt fur Bacteriologie und Parasitenkunde, Band xxiv, No. 15-16, pp. 569-570. 

(5) Experimental Yellow Fever at the Inoculation Station of the Sanitary Depart- 
ment of Havana, with a view to Producing Immunization. "American Medicine." 
Vol. II, No. 21, November 23, 1901. 

(6) "Experimental Yellow Fever." Transactions of the Association of American 
Physicians, Vol. xvi, 1901. 

(7) Sur un cas de tetanus chez l'homme par inoculation accidentelle produits soluble 
du bacille de Nicolaier. Comtes Rendus, etc., de la Societe Biologic Tome V. 
1893, pp. 844-46. 

(8) Report of the Commission appointed to investigate the cases of tetanus in St. 
Louis, following the administration of diphtheria antitoxin. St. Louis Medical 
Review, November 23, 1901. 

(9) Zeitschrift fur Hygiene, 1901, Bd. x, S. 283. 

(10) Loc. cit. 

(11) Loc. cit. 



Chapter 8. 

RECENT RESEARCHES CONCERNING THE ETIOLOGY, PROPAGA- 
TION, AND PREVENTION OF YELLOW FEVER, BY THE UNITED 
STATES ARMY COMMISSION (THREE CHARTS). 

By Walter Reed, M. D., Surgeon, United States Army, President of the Commission. 
[From The Journal of Hygiene, Vol. II, No. 2, April, 1902.] 

The efficient control of the spread of yellow fever is a matter of 
such vast practical importance, both from the hygienic and com- 
mercial point of view — not only for the countries where this disease 
prevails as an epidemic, but also for those in which, after importa- 
tion, it may assume epidemic proportions — that it has seemed appro- 
priate to bring together in this paper a summary of the work thus 
far accomplished by the United States Army Commission 1 on the 
island of Cuba, during the years 1900 and 1901, in order that English 
and Colonial readers who have not, perhaps, had access to the 
original contributions published in different American journals, may 
be able to form an intelligent opinion concerning the permanent value 
of this work. It will also afford opportunity for recording the more 
recent confirmatory observations made by others concerning the mode 
of transmission of yellow fever discovered by the commission, and 
for calling attention to the results already obtained by the United 
States Army Medical Department in the suppression of this disease, 
especially in the city of Habana, through the enforcement of sanitary 
measures based on these later researches. 

The American commission was organized in May, 1900, and began 
its investigations during the following month (June), being equipped 
with suitable laboratory facilities for practical work, both at the 
military garrison of Columbia Barracks, near Quemados, Cuba, and 
also in the city of Habana. As yellow fever was already prevailing 
at the time of our arrival in Cuba suitable material for the scientific 
study of this disease was immediately available. 

THE ETIOLOGY OF YELLOW FEVER. 

Before giving the results of our investigations it may be well to 
recall the situation as regards the etiology of yellow fever at that 
time. Briefly it may be said that the claims of all investigators for 
the discovery of the specific agent of yellow fever — since modern 
bacteriological methods had come into use — had been disproved by 
the exhaustive observations of Sternberg (1), published in 1890, ex- 
cept that made by Sanarelli (2) for a small, motile bacillus isolated 
by him from the blood drawn during life in 2 of 6 cases of yellow 
fever, and from the blood and organs after death in 7 of 12 
cases of this disease (58 per cent), studied at Montevideo and Rio de 

* The members of this commission were Maj. Walter Reed, Surgeon, United States Army, and Drs. 
James Carroll, A. Agramonte, and the late Dr. Jesse W. Lazear, Contract Surgeons, United States Army. 

79965°— S. Doc. 822, 61-3 11 161 



162 YELLOW FEVEK. 

Janeiro, Brazil. The results obtained, however, by those who had 
promptly undertaken to investigate Sanarelli's claim for the specific 
character of Bacillus icteroides, seemed to show a lack of agreement 
such as has never been reported, as far as the writer can recall, in 
connection with the supposed specific cause of any of the other acute 
infections. Thus while Achinard and Woodson (3) had, during the 
epidemic of 1897 in New Orleans, La., isolated a bacillus, claimed by 
them to be identical with B. icteroides, from the venous blood in 4 
out of 5 cases, and from yellow fever cadavers in 32 out of 39 
cases (82 per cent), Portier (4), working in the same city and during 
the same epidemic, could only obtain this bacillus 3 times in 
51 autopsies, and failed to obtain it at all in cultures made from 
the venous blood during life in 10 cases. Again, while Wasdin and 
Geddings (5), in the city of Habana, were able to cultivate B. icteroides 
from blood withdrawn from the lobe of the ear, "not earlier than the 
third day of the disease' 7 in 13 of 14 cases (92.8 per cent), and to 
find it in 85.7 per cent of their necropsies, Agramonte (6), studying 
the disease on the island of Cuba, failed to isolate B. icteroides in a 
single instance from blood drawn from the lobe of the ear in 37 cases 
or from the blood drawn from a vein at the bend of the elbow in 
31 cases at various stages of the disease. The latter observer, how- 
ever, reported finding this bacillus at autopsy in 11 of 35 cases (31.4 
per cent). Without going further into detail, we may say that the 
results obtained byLutz (7) and de Lacerdaand Ramos (8) in Brazil, 
and by Matienzo (9) in Mexico, were equally conflicting and unsatis- 
factory. 

Under these circumstances it seemed to the members of the com- 
mission of the first importance to give their entire attention to the 
bacteriological study of the blood of those sick with yellow fever and 
of the blood and organs of yellow-fever cadavers, having especially in 
view the isolation of B. icteroides. We were thus able during June, 
July, and August to take repeated cultures from the blood during life 
in 18 cases of yellow fever, adopting the usual method employed in 
withdrawing blood from a vein at the bend of the elbow, and trans- 
ferring the blood at once, in quantities of 0.5 c. c, to each of several 
tubes containing 10 c. c. of nutritive bouillon which were afterwards 
incubated at 37° C. for a period of one week. In 7 cases, 4 of which 
were designated as "mild" yellow fever and 3 as "well-marked" 
yellow fever, only 1 culture was made from the blood in each 
case, viz, in 2 cases on the first dav; in 1 case on the second 
day; in 3 cases on the third day; and in 1 case on the fourth day. 
In the remaining 11 cases, diagnosed as "severe" yellow fever, 
of whom 4 died, more frequent cultures were taken from the blood, 
these varying from 2 to 6 cultures on as many different days of the 
disease. In 2 of the fatal cases cultures were made each dav from the 
commencement of the attack and including the day on which death 
occurred. 

The negative result of these numerous cultures taken from the 
blood of cases of yellow fever, as regards the presence of B. icteroides, 
was reported in a "Preliminary note" presented at the meeting of the 
American Public Health Association (10), held in Indianapolis, Ind., 
October 22-26, 1900. To these 18 cases we can now add 6 other 
cases, or a total of 24, from which blood cultures have been made 
during life with negative results. 



YELLOW FEVER. 163 

The importance of this negative finding as regards the growth of 
any specific bacterium will be better appreciated when it is seen, as I 
shall soon have occasion to point out, that yellow fever may be pro- 
duced in nonimmune human beings by the subcutaneous injection of 
a small quantity (0.5-2 c. c.) of blood withdrawn from the venous 
circulation of a patient suffering with this disease. 

In addition to the results above recorded, the careful study of 11 
autopsies was equally barren as to the presence of any particular 
micro-organism, although the quantity of material with which our 
tubes were inoculated was greater than is usually made use of at 
autopsies. 

In a word, then, the careful bacteriological study which the com- 
mission had made in cases of yellow fever had given no indications 
as to the presence of the specific agent of this disease. The same may 
be said concerning the result of numerous microscopic examinations 
of fresh and stained specimens of blood which we had in the mean- 
while studied with a view of finding possibly some intracellular or 
extracellular body. Apparently no body, bacterial or protozoan, 
which could be brought into view with a one-twelfth Zeiss immersion 
objective, was present in the blood of these cases. 

Although displaced from the order in which the following observa- 
tions were made, it will be best to present, at this time, the results of 
the experiments which were later carried out by the commission on 
nonimmune human beings by means of the subcutaneous injection of 
blood, withdrawn during the active stage of the disease, as these results 
bear so directly upon the subject which we are now considering, viz, 
the etiology of yellow fever. 

The only reference that I can find in the literature relative to an 
attempt to convey yellow fever in this way is cited by Sternberg (11), 
who states that at Veracruz, Mexico, in 1887, he saw Dr. Ruis inject 
into a nonimmune individual a hypodermic syringeful of blood drawn 
from a case of yellow fever on the eighth day of the disease. The 
result was negative, as was also the result of two other attempts 
related to him by Ruis. 

Our own observations, undertaken for the purpose of ascertaining 
whether an attack of yellow fever could be induced in a second indi- 
vidual by the injection of a small quantity of blood, embrace experi- 
ments made on 12 American soldiers and Spanish immigrants, all 
nonimmune individuals. 

These observations may be divided into the following classes: 

(1) Injection of the fresh blood taken from a vein at the bend of 
the elbow. (2) Injection of partially defibrinated blood. (3) Injec- 
tion of partially defibrinated blood heated for 10 minutes at 55° C. 
(4) Injection of blood serum previously diluted with sterilized water 
and filtered slowly through a Berkefeld laboratory filter. 

The table following (I) gives the results of these several inoculations. 



164 



YELLOW FEVEK. 
Table I. 



No. of 
case. 


Quantity and material used. 


Day of 
disease. 


Date of 
inoculation. 


Result. 


Date of 

attack. 


I 


2 c. c. fresh blood 


Second 

...do.... 


Dec. 26,1900 
Jan. 4, 1901 
Jan. 8, 1901 
Jan. 22,1901 
Jan. 25,1901 
Oct. 15,1901 
do 

do 

do 

do 

do 

. ..do . 


Negative.. 

Positive. . . 

...do 

...do 

...do 

...do 

Negative.. 

...do 

...do 

Positive... 
...do 

Negative.. 
Positive. . . 




II 


do 


Jan. 8, 1901 


III 


1.5 c. c. fresh blood 


First 

Second 

...do 

Third 

...do 

...do 

...do 

...do 

...do 

...do 


IV 


0.5 c. c. fresh blood 




V 
VI 
VII 

VIII 

ix- 

X 

XI 

XII 


1 c. c. fresh blood 

075 c. c. partially defibrinated blood 

1.5 c. c. partially defibrinated blood heated 
for 10 minutes at 55° C. 

Same as No. VII 

do 

1.5 c. c. of filtered blood serum 

Same as No. X 

(Same as No. X 


Jan. 28,1901 
Oct. 20,1901 

Oct. 19,1901 
Do. 

J0ct. 23,1901 


\2 c. c. fresh blood 


Fourth. . . . 


Oct. 22,1901 









By an examination of this table it will be seen that of the seven 
individuals who received subcutaneously the fresh or partially defi- 
brinated blood in quantities of 0.5-2 c. c, six (85.7 per cent) developed 
an attack of yellow fever within the usual period of incubation of the 
disease. 

These results are of very great interest as demonstrating that the 
specific agent of yellow fever is present in the blood, at least during the 
first, second, and third days of the attack. 

Another important point brought out by these experiments was 
that the blood which conveyed the disease did not contain any bac- 
terium which would grow on our usual laboratory media. 

In order to establish this fact, as soon as blood had been injected 
into the nonimmune subject, additional blood was, at once, withdrawn 
in considerable quantity and transferred to tubes of nutritive bouillon. 
In one instance, where 2 c. c. of blood had been drawn into the syringe, 
0.5 c. c. of this sufficed, when injected, to produce a severe attack of 
yellow fever, after 73 hours' incubation, while the remaining 1.5 c. c. 
transferred immediately to four tubes of bouillon gave no growth, 
except that from one tube we isolated on the fourth day Staphylo- 
coccus pyogenes citreus, found by us to be a common skin-contami- 
nating organism in Cuba. 

Table I further shows that the specific agent contained in the blood 
is destroyed or attenuated by heating the latter at 55° C. for 10 min- 
utes, so that the injection of 1.5 c. c. of this heated blood was harm- 
less (cases VII, VIII, and IX), while the injection of 0.75 c. c. of the 
same blood unheated sufficed to promptly induce an attack of yellow 
fever in a "control" individual (case VI). 

Of not less interest was the fact brought out by these observations 
that yeUow fever can be produced by the injection of a small quantity 
of bacteria-free serum filtrate, obtained by passing the diluted serum 
through a Berkefeld laboratory filter (cases X and XI), and further 
that the blood of a case of yellow fever, thus produced, when injected 
into a third nonimmune subject will promptly bring about an attack 
of this disease (case XII); thus demonstrating that the specific agent 
of yellow fever can find its way through the pores of a filter which ordi- 
narily serves to prevent the passage of all known bacteria. 

I have elsewhere (12) in conjunction with one of my colleagues 
(Carroll) discussed the facts here presented more at length and will 
limit myself, therefore, to the remark that these experiments appear 



YELLOW FEVER. 165 

to indicate that yellow fever, like the foot-and-mouth disease of 
cattle, is caused by a micro-organism so minute in size that it might 
be designated as ultramicroscopic. 

THE PROPAGATION OF YELLOW FEVER. 

Prior to the time at which the foregoing observations were made 
the commission had already turned its entire attention to the possible 
solution of the problem of the propagation of yellow fever, being 
induced thereto, not only by the fruitlessness of the investigations 
made thus far along bacteriological lines, but, also, by reason of cer- 
tain facts which seemed to call for a better interpretation than had 
hitherto been accorded them. 

Without entering into details, I may say that, in the first place, the 
commission saw, with some surprise, what had so often been noted in 
the literature, that patients in all stages of yellow fever could be cared 
for by nonimmune nurses without danger of contracting the disease. 
The noncontagious character of yellow fever was, therefore, hardly to 
be questioned. 

In the second place, it had been observed that patients discharged 
from the wards during early convalescence could be brought into 
intimate association with nonimmune individuals without thereby 
establishing fresh foci of the disease. This did not seem to indicate 
that any specific agent was present in the excreta of the sick. 

Again, it has been noted that in certain cases of this disease no 
growth had been obtained on the ordinary laboratory media, either 
by frequent cultures from the blood during life or from the blood 
and organs after death. 

Further, in the course of an investigation which the commission 
were able to make during the last week of July, 1900, concerning the 
origin and spread of a small epidemic of yellow fever that had 
appeared in a military garrison, numbering about 900 men, at Pinar 
del Rio, Cuba, they had seen that by reason of the false diagnosis of 
"pernicious malarial fever" which had been given to these cases no 
disinfection of bedding or clothing had been carried out; and yet 
there was no indication that this neglect had contributed in the 
least to the spread of the disease; nor had any harm come to those 
nonimmunes who had slept in the beds vacated by the sick, or 
washed the supposedly infected garments of those who had recovered 
or died of this disease. 

Putting these various data together, it seemed probable that more 
progress might be made if attention should be turned to the mode of 
transmission of yellow fever, especially as our own observations had 
caused us to seriously doubt the usually accepted belief of the con- 
veyance of this disease by means of fomites. 

Then, too, the endemic curve of yellow fever in the city of Habana, 
and its well-known epidemic curve in the United States, appeared to 
be more intimately associated with and more affected by the rise and 
fall of the annual temperature curve than was to be seen in any of 
the acute infections, except malarial fever. The peculiar behavior 
of this disease (if I may use the expression) in rapidly spreading in 
certain localities, when introduced, as contrasted with its failure to 
propagate itself in other places, where the conditions for its increase 
were apparently just as favorable, seemed to point in the strongest 



166 YELLOW FEVEK. 

manner to the necessity for some special agent or intermediate host 
in the dissemination of its specific cause. If malarial fever — a dis- 
ease so much affected by temperature conditions — required the 
agency of a special genus 'of mosquito for its propagation, as had in 
recent years been so brilliantly worked out by Ross, Grassi, Bas- 
tianelli, Bignami, and others, it did not seem unreasonable to sup- 
pose that yellow fever — a disease so plainly controlled by seasonal 
conditions — might also depend on some such agent for its spread. 
Influenced by this line of reasoning, the commission began, during 
the second week of August, 1900, its observations relative to the 
propagation of yellow fever by means of the bite of a certain species 
of mosquito — Stegomyia fasciata. 

The work along this line was carried forward so rapidly that, within 
30 days, 11 individuals had been bitten by infected Stegomyia, 
of whom two x developed well-marked attacks of yellow fever within 
the usual period of incubation, and under such circumstances as to 
positively exclude in one case any other possible source of infection. 

Appreciating fully the importance of this discovery and in order to 
exclude all other possible sources of infection in our future observa- 
tions, it was now determined to establish a special experimental 
station where further observations could be made on nonimmune 
human beings, both as to the propagation of yellow fever by means 
of the bite of the mosquito as well as by exposure to the most inti- 
mate contact with infected clothing and bedding, and this under the 
strictest enforcement of military quarantine. With the approval 
and assistance of the military governor of the Island of Cuba, this 
experimental station was ready for occupancy on November 20, 1900, 
and was continuously occupied until March 1, 1901. 

As the results obtained at this station have already been published 
(13) in full elsewhere, I will here only present a brief account, first of 
the experiments with fomites and afterwards of those made with in- 
fected mosquitoes. 

ATTEMPTS AT INFECTION BY FOMITES. 

I quote from a paper which the writer presented for the commission 
at the meeting of the Pan-American Medical Congress, 2 held in 
Habana, Cuba, February 4-7, 1901: 

For this purpose there was erected at Camp Lazear a small frame house consisting 
of one room, 14 by 20 feet, and known as "building No. 1," or the ''infected clothing 
and bedding building." The cubic capacity of this house was 2,800 feet. It was 
tightly sealed within with "tongued and grooved" boards, and was well battened on 
the outside. It faced the south and was provided with two small windows, each 26 by 
34 inches in size. These windows were both placed on the south side of the building, 
the purpose being to prevent, as much as possible, any thorough circulation of the 
air within the house. They were closed by permanent wire-screens of 0.5 mm. mesh. 
In addition a sliding glass sash was provided within and heavy wooden shutters with- 
out; the latter intended to prevent the entrance of sunlight into the building, as it 
was not deemed desirable that the disinfecting qualities of sunlight, director diffused, 
should at any time be exerted on the articles of clothing contained within this room. 
Entrance was effected through a small vestibule, 3 by 5 feet, also placed on the southern 
side of the house. This vestibule was protected without by a solid door and was 
divided in its middle by a wire-screen door, swung on spring hinges. The inner 
entrance was also closed by a second wire-screen door. In this way the passage of 

*One of these cases was tliat of Dr. James Carroll, Contract Surgeon, U. S. A., a member of the 
commission. 
*Loc. Cit. 



YELLOW FEVER. 167 

mosquitoes into this room was effectually excluded. During the day and until after 
sunset the house was kept securely closed, while by means of a suitable heating 
apparatus the temperature was raised to 92°-95° F. Precaution was taken at the same 
time to maintain a sufficient humidity of the atmosphere. The average temperature 
of this house was thus kept up at 76.2° F. for a period of sixty-three days. 

November 30. 1900, the building now being ready for occupancy, three large boxes 
filled with sheets, pillowcases, blankets, etc., contaminated by contact with cases of 
yellow fever and their discharges were received and placed therein. The majority 
of the articles had been taken from the beds of patients sick with yellow fever at Las 
Animas Hospital,- Habana, or at Columbia Barracks. Many of them had been pur- 
posely soiled with a liberal quantity of black vomit, urine, and fecal matter. A dirty 
"comfortable " and a much-soiled pair of blankets, removed from the bed of a patient 
sick with yellow fever in the town of Quemados were contained in one of these boxes. 
The same day, at 6 p. m., Dr. R. P. Cooke, acting assistant surgeon, United States 
Army, and two privates of the Hospital Corps, all nonimmune young Americans, 
entered this building and deliberately unpacked these boxes, which had been tightly 
closed and locked for a period of two weeks. They were careful at the same time to 
give each article a thorough handling and shaking, in order to disseminate through the 
air of the room the specific agent of yellow fever, if contained in these fomites. These 
soiled sheets, pillowcases, and blankets were used in preparing the beds in which the 
members of the Hospital Corps slept. Various soiled articles were hung around the 
room and placed about the bed occupied by Dr. Cooke. 

From this date until December 19, 1900, a period of 20 days, this room was occupied 
each night by these three nonimmunes. Each morning the various soiled articles 
were carefully repacked in the aforesaid boxes, and at night again unpacked and dis- 
tributed about the room. During the day the residents of this house were permitted 
to occupy a tent pitched in the immediate vicinity, but were kept in strict quarantine. 
* ****** 

December 19 these three nonimmunes were placed in quarantine for five days and 
then given the liberty of the camp. All had remained in perfect health, notwith- 
standing their stay of 20 nights amid such unwholesome surroundings. 

During the week December 20-27 the following articles were also placed in this 
house, viz, pajamas suit, 1; undershirts, 2; nightshirts, 4; pillow slips, 4; sheets, 6; 
blankets, 5; pillows, 2; mattress, 1. These articles had been removed from the per- 
sons and beds of four patients sick with yellow fever and were very much soiled, as 
any change of clothing or bed linen during their attacks had been purposely avoided, 
the object being to obtain articles as thoroughly contaminated as possible. 

From December 21, 1900, till January 10, 1901, this building was again occupied 
by two nonimmune young Americans under the same conditions as the preceding 
occupants, except that these men slept every night in the very garments worn by 
yellow fever patients throughout their entire attacks, besides making use exclusively 
of their much-soiled pillow slips, sheets, and blankets. At the end of 21 nights of 
such intimate contact with these fomites, they also went into quarantine, from which 
they were released five days later in perfect health. 

From January 11 till January 31, a period of 20 days, "building No. 1" continued 
to be occupied by two other nonimmune Americans, who, like those who preceded 
them, have slept every night in the beds formerly occupied by yellow fever patients, 
and in the nightshirts used by these patients throughout the attack without change. 
In addition, during the last 14 nights of their occupancy of this house they had slept 
each night with then pillows covered with towels that had been thoroughly soiled 
with the blood drawn from both the general and capillary circulation on the first day 
of the disease, in the case of a well-marked attack of yellow fever. Notwithstanding 
this trying ordeal these men have continued to remain in perfect health. 

The attempt which we have therefore made to infect "building No. 1 " and its seven 
nonimmune occupants during a period of 63 nights has proved an absolute failure. 

INFECTION BY MOSQUITOES. 

While the experiments with fomites were being carried out in 
"Bunding Xo. 1/' certain nonimmune individuals wjio were lodged 
in tents, in a separate part of the camp, were being subjected, with 
their full consent, to the bites of mosquitoes which had previously fed 
on the blood of cases of }^ellow fever occurring in the city of Havana. 
Thus during the period from December 5, 1900, to February 7, 1901, 
we had subjected to this method of infection 12 nonimmune subjects, 



168 



YELLOW FEVER. 



who had previously passed their full record of quarantine in this 
camp. Of these 10, or 83.3 per cent, experienced attacks of yellow 
fever and always within the period of incubation of this disease. 

The following Table II gives the necessary data concerning these 
observations : 

Table II. 



No. of 
case. 


Days in 
quaran- 
tine. 


Inoculation. 


Method of 
inoculation. 


Period 
of incu- 
bation 

in 
hours. 


Result. 


Order 
of oc- 
cur- 
rence. 


Date of 
occurrence. 


Hour. 


Date. 


I 


15 
9 
19 
21 
32 
31 
22 
69 
74 
6 
78 
25 


2p. m 


Dec. 5, 1900 
Dec. 8, 1900 
Dec. 9, 1900 
Dec. 11,1900 
Dec. 21,1900 
Jan. 8, 1901 
Dec. 30,1900 
Jan. 19,1901 
Jan. 25,1901 
Jan. 31.1901 
Feb. 6, 1901 
Feb. 7, 1901 


Mosquito 

do 

do 

do 

do 

do 

do 

do 

do 

do 

do 

do 


81* 
137 
83J 
91J 
95 

" 94 j' 

95| 

74^" 

78" 
70 


Positive 

do 

do 

do 

do 

Negative. . . 

Positive 

do 

Negative. . . 

Positive 

do 

do 


I 

III 

II 

IV 

V 

VI 

VII 

VIII 

IX 

X 

XI 

XII 


Dec. 8, 1900 
Dec. 13,1900 
Dec. 12,1900 
Dec. 15,1900 
Dec. 25,1900 

Jan. 3,1901 
Jan. 23,1901 

Feb. 3,1901 
Feb. 9, 1901 
Feb. 10,1901 


II 


4p. m 


III 
IV 

V 


10.30 a. m 

4.30 p. m 

12m 


VI 

VII 

vni 

IX 

X 

XI 

XII 


10 a. m 

11 a. m 

8.30 p. m 

10.30 a. m 

9.30 a.m. 

11 a.m 

2p. m 









The positive results obtained, therefore, by this mode of infection 
stand in striking contrast to the negative experiments made with 
fomites. Indeed, cases VIII and XI of Table II had each slept 21 
nights in the garments of yellow fever patients while occupants of 
''building No. 1." As they had remained in perfect health at Camp 
Lazear for yet 30 days longer, they were at the expiration of this 
time bitten by infected mosquitoes solely for the purpose of testing 
their immunity and with the result that an attack of yellow fever 
promptly followed in each case. 

It should be borne in mind, also, that of the nonimmune residents 
at Camp Lazear, while all lived under the same hygienic conditions, 
only those individuals developed yellow fever who were purposely 
bitten by contaminated mosquitoes, or injected with the blood of 
those sick with this disease. Moreover, the precision with which the 
infection of the individual followed the bite of the mosquito left 
nothing to be desired in order to fulfil the requirements of a scientific 
experiment. 

Case V of Table II is of especial interest, when taken in connection 
with the failure to induce the disease by contact with fomites. 

This individual, having been quarantined for 32 days a,t Camp 
Lazear, volunteered to enter a newly erected building in which 
15 contaminated mosquitoes had just been freed. His first visit 
was at noon, December 21, 1900, and the length of his stay 30 min- 
utes. At 4.30 p. m. the same day he again entered this building and 
remained 20 minutes. The following day at 4.30 p. m. he for the 
third time visited this room and remained 20 minutes. During 
each of these visits he was bitten by mosquitoes. He did not enter 
the building again, nor was he exposed to any other source of infec- 
tion. Nevertheless at the expiration of 3 days and 23 hours, or 
at 6 a. m. December 25, 1900, he was suddenly seized with an attack 
of yellow fever, which proved to be severe in character. That the 
infection was occasioned by the bites of contaminated mosquitoes was 
plainly shown by the immunity from the disease enjoyed by two 



YELLOW FEVER. 169 

nonimmune "controls/' who, protected only by a wire-screen parti- 
tion, had been d resent at each of the subject's visits and who under 
the same conditions of security against the bites of the infected mos- 
quitoes continued to sleep in and breathe the com mom atmosphere 
of this room for yet 18 nights. 

To the positive cases contained in Table II, which were produced at 
Camp Lazear, we are now able to add 4 other cases of yellow fever 
occasioned by the bites of infected mosquitoes, thus making a total of 
14 cases, in each of which happily recovery followed. 

A very important point brought out by these observations is that 
an interval of about 12 days or more after contamination appears to 
be necessary before the infected Stegomyia is capable of conveying 
the disease to a susceptible individual. Repeated experiments made 
with insects which had bitten yellow fever patients 2 to 10 days pre- 
viously were always negative, although these same insects were 
proven capable of conveying the disease after having been kept until 
17 to 24 days had elapsed. Our observations (14) further demonstrate 
that mosquitoes that have been kept for periods varying from 39 to 
57 days after contamination are still capable of conveying the disease, 
and further that infected Stegomyia may survive for a period of at 
least 71 days. This will explain how the contagion of yellow fever 
may cling to a building, although it has been vacated for a period of 
two or more months. 

Bearing in mind that the observations made by means of blood 
injections (Table I) were only undertaken after we had succeeded in 
demonstrating that the disease could be conveyed by the bites of 
infected Stegomyia, it will be seen that our study of the method of 
propagation of yellow fever, at Camp Lazear, sufficed to prove very 
definitely that, while the natural mode of transmission of this disease 
is through the bites of infected mosquitoes, yellow fever may also be 
conveyed, like malarial fever, by the injection of a small quantity of 
blood taken from the veins of an individual suffering with this disease. 

Per contra, our observations show that, notwithstanding the com- 
mon belief in this mode of transmission, yellow fever can not be 
induced in the nonimmune individual even by the most intimate con- 
tact with contaminated articles of clothing and bedding. 

Although the investigations made at Camp Lazear were only con- 
cluded one year ago, already confirmatory evidence of the strongest 
character has been furnished in a series of experiments carried out by 
Guiteras (15) at the inoculation station of the sanitary department 
of Habana. 

I may be pardoned for quoting the paragraph with which Guiteras 
begins his contribution. He says : ' ' The favorable results obtained by 
the United States Army commission in their experiments with yellow 
fever, the continued series of mild cases resulting from these experi- 
ments without a death, suggested veiy naturally the continuation of 
their work on a larger scale; not with a view to control or confirm the 
conclusions of the commission, for anyone who had followed their 
work with unprejudiced attention must have concluded that their 
solution of the problem of the etiology of yellow fever was final ; but 
rather in the hope of propagating the disease in a controllable form, 
and securing amongst the recently arrived immigrants immuniza- 
tion, with the minimum amount of danger to themselves and the 
community." 



170 



YELLOW FEVER. 



Of a total of 42 individuals inoculated by Guiteras 25 were rejected 
by him by reason of having been bitten by insects that had been 
applied to cases of fever about which the diagnosis was in doubt. The 
following table, therefore, only includes 17 persons who were bitten 
by Stegomyia that had previously fed on unmistakable cases of yellow 
fever at intervals of 14 to 36 days before being applied to the non- 
immune subject. 

Table III. 



No. 

of 

case. 


Date of inoc- 
ulation. 


Mode of inoculation. 


Result. 


Period of incuba- 
tion. 


1 


Feb. 23,1901 
Aug. 4,1901 
do 






3 days, 10 hours. 


2 


do 




3 


do 


do 




4 


Aug. 7,1901 
Aug. 8,1901 
do 


do 


.do. 




5 


do 




4 days, 5 hours. 
3 days, 3 hours. 


6 


do 


do 


7 


Aug. 7,1901 
Aug. 9,1901 
Aug. 10,1901 
do 


do 




8 


do 




5 days, 3 hours. 


9 


do 




10 


...do.... 


do 

do.... 




11 


do 


do 




12 


Aug. 13,1901 
do 


do ... 




3 days, 19 hours. 


13 


...do.... 




14 


Aug. 14,1901 
do 

Aug. 22,1901 
Aug. 24,1901 


do 

do 

...do.... 




3 days, 21 hours. 
5 days, 21 hours. 
3 days. 


15 


do 


16 


.do 


17 


do 













A more complete confirmation of the results obtained by the 
American commission could not be furnished than the data contained 
in the foregoing table, since they show that of 17 individuals who 
were bitten by infected Stegomyia fasciata, 8 (47 per cent) developed 
the disease. Most unfortunately, in three of these cases very grave 
symptoms ensued, such as black vomit and suppression of the urine, 
which eventuated in the death of the patients. I may add that in the 
hands of Guiteras fomites failed to exert any effect on nonimmunes. 

Whether other species of mosquitoes than Stegomyia are capable of 
conveying the parasite of yellow fever has not as yet been determined 
by the commission; nor have we been able to ascertain whether the 
parasite passes from the mother insect to daughter insects. The 
experiments which we have thus far been able to make for the purpose 
of determining these important points, although negative, have been 
too few in number to warrant any definite expression of opinion. 



THE PREVENTION OF YELLOW FEVER. 

The definite determination of the way in which yellow fever is 
transmitted from the sick to the well furnishes a solution at last of 
that much vexed problem of how to prevent the spread of the disease. 
Even in the absence of more definite knowledge concerning its specific 
agent — knowledge greatly to be desired from the scientific stand- 
point — we are now able, as sanitarians, to direct our efforts along cer- 
tain well-defined lines, with a feeling of security heretofore unknown. 

From the point of view of prevention the situation may be briefly 
summed up in the following conclusion, which was presented by the 
American Army commission to the Pan-American Congress of 1900, 1 

- Loc. cit. 



YELLOW FEVER. 171 

viz, "The spread of yellow fever can be most effectually controlled by 
measures directed to the destruction of mosquitoes and the protection 
of the sick against the bites of these insects." 

This conclusion was the logical outcome of the observations that 
had been made by the commission at its experimental station near 
Quemados, Cuba. 

The importance of the discovery that }^ellow fever is transmitted by 
the bite of a certain species of mosquito did not fail to attract the 
prompt attention of the military governor of the island of Cuba, 
himself a physician and formerly a distinguished member of the 
Medical Department of the United States Army. By his direction 
the theory was at once subjected to a practical test in the city of 
Habana, in which city yellow fever had not failed to make its yearly 
appearance during the past 140 years. 

Under the efficient management of the chief sanitary officer, 
Surg. Maj. Wm. C. Gorgas, United States Army, the sanitary regula- 
tions were so far modified as to require that every patient having yel- 
low fever should not only be quarantined, but that his room should be 
promptly protected with wire screens, so as to prevent the possibility 
of mosquitoes becoming infected by sucking the blood of the patient. 
As a second important measure, a systematic destruction of all mos- 
quitoes in other rooms of the patient's house, as well as in adjoining 
houses, was at once begun, the fumes of pyreihrwn being relied upon 
to stupify the insects, after which they were carefully swept up and 
burned. In other words, Surg. Maj. Gorgas relying upon the well- 
known slow progress of yellow fever sought to destroy all mosquitoes, 
infected or noninfected, within a given radius of each case, while at the 
same time he effectually excluded all mosquitoes from access to the 
sick. If a secondary case occurred, the same hygienic measures 
were vigorously enforced along the lines above indicated. 

As an illustration of what has been accomplished by these newer 
sanitary regulations, I may state that counting from the date when 
they were put into force — viz, February 15, 1901 — Habana was freed 
from yellow fever within 90 days; so that from May 7 to July 1 — 
a period of 54 days — no cases occurred. Notwithstanding the fact 
that on the latter date, and during the months of July, August, and 
September, the disease was repeatedly reintroduced into Habana 
from an inland town, no difficulty was encountered in promptly 
stamping it out by the same measures of sanitation intelligently 
applied both in the city of Habana as well as in the town of Santiago 
de las Vegas, whence the disease was being brought into Havana. 

As a further illustration of the remarkable sanitary victory accom- 
plished over a disease whose progress we had heretofore been powerless 
to arrest, I will close this paper by inviting the reader's attention, first 
to the accompanying Chart I, which shows the average monthly 
mortality from yellow fever in Havana for the 20 years 1880-1899, 
inclusive, and also the mortality by month for the years 1900 and 
1901. I will then ask him to examine Chart II, which shows the 
progress of yellow fever in Habana during the epidemic year, ending 
March 1, 1901, when the sanitary authorities were putting forth every 
effort known at that time to sanitary science in order to control the 
march of the disease; and when he has satisfied himself that no effect 
whatever was produced upon the epidemic of that year, I will invite 
his attention to Chart III, which shows the occurrence of this disease 



172 



YELLOW FEVER. 



CHART I. 

Showing monthly mortality from yellow fever in the city of Havana, for the twenty years, 
1880-1899, and for the years 1900-1901. 



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CHART II. 



173 



Cases and deaths from yellow fever in the city of Havana, for the epidemic year, March 1 
1900, to March 1, 1901 {by month). 



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CHART III. 

Cases and deaths from yellow fever in the city of Havana, for the epidemic year, March 1, 
1901, to March 1, 1902 {by month). 




174 YELLOW FEVER. 

in Habana for the epidemic year March 1, 1901, to March 1, 1902, 
during which year yellow fever was fought on the theory that the 
specific agent of this disease is transmitted solely by means of the 
bites of infected mosquitoes. By carefully comparing the figures 
both as to deaths and cases in these two charts, and recalling that 
between the years 1853 and 1900 there have been recorded in the city 
of Habana 35,952 deaths from yellow fever, he will then be able to 
more clearly appreciate the value of the work accomplished by the 
American Army commission. 

BIBLIOGRAPHY. 

(1) Report on the Etiology and Prevention of Yellow Fever. Washington, 1890. 

(2) La Fiebre Amarilla. Conferencia dada en la Universidad de Montevideo, el 
10 Junio 1897. Reprint. 

(3) Bacteriological Study in the Etiology of Yellow Fever. New York Medical 
Journal, Jan. 28, 1899, pp. 109-114. 

(4) Summary of Pathologic and Bacteriologic Work, at Isolation, New Orleans, La. 
Journal of the American Medical Association, April 16, 1898, pp. 884-888. 

(5) The Etiology of Yellow Fever. Abstract of Report, &c. N. Y. Med. Journal, 
August 26, 1899, pp. 299-302. 

(6) Report upon Bacteriological Investigations in Yellow Fever. The Medical 
News, N. Y., February 10 and 17, 1900. 

(7) Revista d' Igiene e Sanita Publica, xi. No. 13, July, 1900, pp. 474-475. 

(8) La Bacille Icteroide et Sa Toxine. Archives de Medicine Experimental &c, xi., 
1899, pp. 378-398. 

(9) Nota para Servir al estudio bacteriologico de la Fiebre Amarilla. Gaceta Medica 
de Mexico, xxxvi, 1899, pp. 218-230. 

(10) The Etiology of Yellow Fever. A Preliminary Note. The Philadelphia Med. 
Journal, October 27, 1900. 

(11) Yellow Fever. Buck's Reference Uand-boolc of the Medical Sciences, Vol. vni, 
1889, p. 48. 

(12) The Etiology of Yellow Fever. A Supplementary Note. American Medicine, 
Vol. m, No. 8, February 22, 1902, pp. 301-305. 

(13) The Etiology of Yellow Fever. An Additional Note. Journal of the American 
Medical Association, February 16, 1901. 

(14) Experimental Yellow Fever. Transactions of the Association of American 
Physicians, Vol. xvi, 1901. 

(15) Experimental Yellow Fever at the Inoculation Station of the Sanitary Depart- 
ment of Havana. American Medicine. Vol. n, No. 21, 1901, pp. 809-817. 




DR. JAMES CARROLL. 



PART III— THE PUBLICATIONS OF JAMES CARROLL, ASSISTANT SUR- 
GEON, UNITED STATES ARMY, IN REGARD TO YELLOW FEYER. 

[Published after the death of Maj. Walter Reed.] 



Chapter 1. 

THE TRANSMISSION OF YELLOW FEVER. 1 

By James Carroll, M. D., 
Assistant Surgeon, United States Army. 

[Read at the forty-fourth session of the American Medical Association, in the section on practice of medi- 
cine, and approved for publication by the executive committee: Drs. J. M. Anders, Frank A. Jones, and 
W. S. Thayer.] 

Several American observers have noted that during the yellow 
fever outbreaks mosquitoes were very numerous, among them 
Rush(l),at Philadelphia in 1797; Dr. Weightman(2), of the United 
States Army, at St. Augustine, Fla., in 1839; Dr. Wood (3), at Center- 
ville, Miss., in 1853. Dr. E. H. Barton(3) states "that at Clinton, 
La., in 1853, mosquitoes were uncommonly numerous night and day." 
At Trinity, La., in the same year, when sawdust was used to fill 
up low places in the streets, the disease was not propagated, though 
many cases were brought there and no precautions were used (3). 
It is hardly necessary to note what the effect of this obliteration of 
puddles would be on the development of mosquitoes. Dr. Beyren- 
heidt(3), of Biloxi, Miss., in reporting a severe epidemic at that place 
in 1853, during which 533 cases and 111 deaths occurred in a popula- 
tion of 5,520, makes the interesting statement that " mosquitoes 
and fleas were very abundant." Dr. Bennett Dowler strongly 
urged drainage of the city of New Orleans, and spoke of the city and 
its environs as " mosquito lands "(4). La Roche (5) states that in 
1793, during the epidemic in Philadelphia, u the narrow streets and 
alleys near the wharves, as, indeed, in many other parts, were in a 
foul state, and the gutters almost everywhere sadly neglected." In 
1794 Rush and others ascribed the fever to exhalations from wharves, 
neglected gutters, and stagnant ponds (5). In 1797, during another 
outbreak in Philadelphia, the condition was practically the same; 
the Academy of Medicine called the attention of the governor to 
the putrid exhalations from the gutters, streets, ponds, and marshy 
grounds of the neighborhood of the city (5). While high temperature, 
low altitude, and the presence of standing water are the conditions 
most favorable to the development of a yellow fever epidemic, there 
are numerous instances on record where the disease after introduc- 
tion spread from house to house throughout the town in places 
where the general conditions of sanitation and drainage were good. 
This is now explained by the habits of the mosquito (Stegomyia 
fasciata), which breeds in standing water, in houses as well as out of 

1 Journal of the American Medical Association, May 23, 1903. 

175 



176 YELLOW FEVEE. 

doors. As a general rule, in ports where yellow fever epidemics first 
appear, the conditions are known to be favorable for the develop- 
ment of enormous numbers of mosquitoes. 

A very interesting observation was made in 1839 in South Africa 
by William Ferguson, then a surgeon in the South African corps, in 
regard to the extension of yellow fever from Sierra Leone (where it 
had been brought on vessels from the West Indies) to Gambia, 
Goree, and Ascension, the subsequent ports of arrival of some of 
these infected vessels. After mentioning an unusually heavy accu- 
mulation of mud and filth in a pit at Ascension, which was said to 
have been the cause of the fever occurring after an unusually heavy 
fall of rain, he makes the following statement: 

(6) It will be observed that at Ascension, at Goree, and at Gambia a period of three 
or four weeks always elapsed betwixt the landing of the sick and the epidemic out- 
breaking of the disease among the population, a degree of uniformity worthy of remark 
whether the conclusions at which I have arrived (that the disease was carried to these 
places on infected vessels) be mistaken or not. 

These outbreaks were accompanied by black vomit and were 
undoubtedly yellow fever of imported origin. 

Just 60 years later Carter (7) made a similar observation in the 
United States, shortening the period slightly and giving cases and 
data. In a later paper (8) he designates the interval between pri- 
mary and secondary cases the period of "extrinsic incubation." 

The known facts regarding the apparent noncontagiousness of the 
disease, the peculiar manner in which it has been seen to pass from 
one house to another without intercommunication of the inhabitants, 
and the numerous points of resemblance between yellow fever and 
malaria, led us to expect results from mosquito inoculations in yellow 
fever. After satisfying ourselves that B. icteroides (Sanarelli) was 
not to be considered, Drs. Reed, Lazear, and myself, in consultation, 
decided that the mosquito theory had many facts to support it and 
could be promptly decided one way or the other. This leads us to a 
consideration of the mosquito theory of Finlay. 

At the session of the Royal Academy of Sciences, Habana, August 
14, 1881, Finlay first gave to the world his memorable theory of the 
transmission of yellow fever by the mosquito, and reported five 
experiments, which are included in the accompanying table, compris- 
ing all of Finlay's and Delgado's positive cases published in 1891. (9) 

Finlay believed (10) that the transfer of the specific agent of the 
disease from patient to nonimmune was effected mechanically by the 
insect's proboscis (14) and that the infection would be conveyed 
immediately if the insect chanced to bite a susceptible person a few 
moments after feeding on a patient in the proper stage of the dis- 
ease. (11) He also thought that the graver forms of yellow fever 
might be produced by the bite of Culex pungens, because the insect 
ingested a larger amount of blood than stegomyia, and consequently 
a greater quantity of the virus would be retained on its proboscis 
(stylet). (11) He ventured the opinion that yellow fever was a sort 
of eruptive fever, and that the seat of the eruption was the endothelial 
lining of the blood vessels, and that the mosquito picked up the inocu- 
lable material from the interior of the blood vessels on its biting appa- 
ratus and transferred the same to the interior of the vessels of the per- 
son subsequently bitten. 



YELLOW FEVER. 



177 











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178 • YELLOW FEVEK. 

In a later paper he assumes that the picking up of these germs by the 
proboscis of the mosquito is selective, because there is nothing to prove 
that other inoculable diseases have ever been so transmitted. From 
four culture experiments, in each of which the head and the pro- 
boscis of a mosquito were dropped into a bouillon tube, he infers that 
the head and the proboscis of the day mosquito possess bactericidal 
properties for ordinary bacteria and fungi with the exception of a 
coccus, which was subsequently (12) claimed to be the specific agent 
of the disease. (13) The sting of the mosquito is suggested as the 
"intermediate host" necessary for some phase of development of 
disease germs. (14) 

As late as 1899 Finlay mentions the isolation of the tetracoccus from 
culture media into which the heads and proboscides of contaminated 
mosquitoes had been dropped, as one of the three results of his experi- 
ments on yellow fever mosquitoes. 

In a paper (13) published in 1895 he announced some very interest- 
ing results obtained with the "tetracoccus." A number of rabbits 
were inoculated intraperitoneally with cultures in bouillon; one of 
these cultures had been obtained from the head and the proboscis of a 
mosquito by placing them in a tube of bouillon five days after the 
insect had bitten a yellow-fever patient; the others came from the 
finger blood and milk of yellow-fever patients. All of the rabbits 
died; some of them showed infarcts of the kidneys, lungs, and liver. 
A rabbit obtained from the country was placed in the stable where 
some of the other rabbits had been kept, and at the end of eight days 
it was found dead. The tetracoccus was obtained from its heart's 
blood. 

Eleven days after the rabbits had been removed from the house 
(the stable is usually a part of the house in Habana) a Spanish wet 
nurse came to spend some time there and on the third day following 
her arrival she was attacked with yellow fever. Mosquitoes had been 
unusually abundant in the house during the whole time the inocu- 
lated rabbits had been kept in it, and we are asked to keep this in 
mind in view of the possible transmission of the disease from animals 
to man. We are told that the blood from the ringer of this woman on 
the third day of her illness gave the "pale yellow tetracoccus," and 
the milk from her breast gave a "white tetracoccus," which proved 
fatal to a rabbit in 15 days. (13) 

While reading the accounts of these experiments one is constantly 
reminded of the pathogenic staphylococci. It is strongly suggested 
(13) that the rabbits died of yellow fever, and it is asserted that the 
experiments justified the assumption that the tetracoccus was the 
"specific germ of yellow fever." 

The statement is also made in this paper that of 100 presumably 
susceptible persons who had received the mosquito inoculation during 
the 14 years previous, only 3 had subsequently died of yellow fever. 
(13) 

I haye been unable to find records of these 100 cases in the library 
of the Surgeon General's Office, and submit those of which the data 
are accessible to me. As these include the cases on which Dr. Finlay's 
claim is based they will suffice for the purpose. The 54 negative cases 
are omitted. 



YELLOW FEVER. 179 

Case 3 was bitten by a mosquito that had been fed on bloody 
excrement from another mosquito that had been found inside the 
mosquito net of a fatal case. The material was ^allowed to dry for 
27 days in the test tube and was then moistened with a little sugar 
and water to prepare it for feeding. (15) There is a marked difference 
between the method of procedure herein described and that given in 
1901, (16) when Dr. Finlay said: 

I applied a nocturnal mosquito and allowed it to fill itself from a case of yellow fever. 
After pricking the side of the insect's abdomen I mixed the blood which escaped 
with a drop of sterilized sirup and fed with it a fresh culex mosquito, and finally- 
applied the latter to a third soldier (July 29). Two days later, July 31, the soldier 
went to the hospital with a fever which was also recorded as "abortive yellow fever." 

This case (L. G. P.) was omitted from the paper published in 1881, 
as stated, but was included in 1891 in the report from which the cases 
here recorded are taken. 

Case 4 is further discussed in English in a footnote on page 368 of 
the Revista de la Asociacion Medico-Farmaceutica, Habana, Feb- 
ruary, 1902. (History of illness vague. Did not go to bed or report 
himself sick.) The first 5 cases were newly arrived soldiers, stationed 
at Cabanas and who were brought to the city of Habana for exami- 
nation once in every 5 days. 

Case 9 is cited by Finlay (17) in refutation of our conclusion (18) 
that the mosquito is not capable of infecting until about 12 days or 
more have elapsed after it has bitten the patient. 

Case 55 was a Spaniard, newly arrived, who lived at a country 
residence. At both attempts to inoculate him the mosquitoes failed 
to bite; nevertheless he was taken sick August 26. Another non- 
immune who occupied an adjoining room was taken sick with similar 
symptoms, a few days later. No further comment is necessary, 
except that the cases of the Army commission and of Dr. Guiteras 
were kept under close observation and strict control. Nearly all of 
Dr. Finlay's cases were exposed to infection in the city of Habana. 
Only four of them come within the recognized periods of incubation, 
viz, Nos. 2, 3, 4, and 66. The first three of these were inoculated in 
Habana in July, 1881, during which month there were 90 deaths 
from yellow fever in that city alone. The last was inoculated in 
August, 1890. In that month 60 deaths from yellow fever are 
recorded for the city of Habana. 

Finlay has published a great many conjectures and speculations 
in regard to yellow-fever transmission. Some of these, such as the 
belief that the disease was transmitted by the mosquito, have been 
proven by our work, but not in accordance with his ideas. I can 
find no evidence that he has produced a single case of yellow fever 
by his inoculations. In the first place the mosquito is incapable of 
transmitting the disease in so short a period as 2 to 5 days after 
biting the patient. In the second place 7 days must be placed as the 
extreme limit of incubation in the human being. Our longest period 
was between 5 and 6 days. Finlay conveniently puts the ordinary 
limit of yellow-fever incubation between 5 and 22 days. (14) The 
efficiency of the 5-day quarantine regulation proves that incubation 
in man certainly does not extend over 6 days, or 7 at the extreme, 
and in the 30 experimental cases recorded by ourselves and Guiteras 
the former period has never been exceeded. 



180 YELLOW FEVER. 

Table 2. — Negative mosquito inoculations of the Army commission. 



No. 


Character of attack 
and number of pa- 
tients bitten. 


Day of disease. 


Interval 
in mos- 
quito 
(room 
tempera- 
ture). 


Date of appli- 
cation of 
mosquito. 


Number 
of mos- 
quitoes 
applied. 


Remarks. 


1 


Mild, 1 


Seventh 

Fifth.. 


Days. 
5 
5 
6 
6 
8 
10 
3 

13 
3 
6 
4 
2 
3 
6 
11 
6 
9 

14 
12 
10 
15 
13 
10 
' 13 
16 
12 
12 
15 
18 
4 
11 
122 


Aug. 11,1900 
do 

Aug. 12,1901 
do 

Aug. 14,1901 
Aug. 16,1901 
Aug. 18,1901 

JAug. 19,1901 
I Aug. 25,1901 

pov. 20,1901 

[Nov. 23,1901 

JNov. 26,1901 

JNov. 29,1901 

Nov. 26,1901 
Nov. 29,1901 

JDec. 2,1901 

Nov. 26, 1901 
Nov. 29,1901 
Dec. 2,1901 
Dec. 17,1901 
Dec. 24,1901 
Jan. 25,1901 


1 
1 
1 
1 
1 
1 
1 

2 
1 

1 

1 

1 

1 

1 
1 

2 

1 
1 
2 

14 
7 

12 


Negative. 


?, 


Very mild, 1 


3 
4 

5 
6 

7 


do 

do 

do 

do 


do 

do 

do 

do 

Second 

Fifth.. 


Do. 
Do. 
Do. 
Do. 
Do. 






8 


\Severe, 1 


First.... 

Second 

First 


Do. 




(Fatal, 1 




q 


^Mild, 1 


Do 






Second 

Third . 






f....do 




10 


f...do 

[ do... 


do 

Fifth.. 


Negative; repetition. 




f....do 


Third 




n 


{....do 

1. ...do 


do 

Fifth 


Do. 






Third 




12 


\Well marked, 1 

/Moderate, 1 


Second 

Third... 


Do. 


13 
14 
15 

16 


\Well marked, 1 

Severe, 1 

do 

/....do 

\ Fatal, 1 


Second 

do r... 

do 

do 

Third 


Do. 

Do. 
Do. 

Do. 


17 


Well marked, 1 


do 


Do. 


18 
19 
20 


do 

do 

Mild, 1 


do 

do 


Do. 
Do. 
Do. 


21 


do 

Very mild 


do 

Eighth hour. . 


Do. 

Do. 









l 82° F. 

Note.— The subjects of Experiments Nos. 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and 21 were proved to be 
susceptible by subsequent experimental infection. No. 22 declined a second test. In Experiments 20 and 
21 the same set of insects and the same subject were used. Four of these insects infected this man six days 
later, on December 30, 1900. 

In a letter of August 20, 1901, Dr. Finlay (19) states he was con- 
vinced that extension of the interval between the application of the 
mosquito to the patient, and subsequently to the nonimmune, would 
develop a severe attack, such as he was anxious to avoid. One can 
sympathize with the humane feeling that prompted him to forego 
positive proof of his theory rather than run the risk of producing a 
severe attack, but it is a fact that on August 22, 1901, two days later 
than the date of that letter, I saw Dr. Finlay apply to a nonimmune 
two mosquitoes that had been kept 34 days after contamination. (20) 

I have been impelled to look up the literature of this subject 
because I have seen several times of late the statement of Dr. Finlay 
that the Army Yellow Fever Commission has tacitly ignored his right 
of priority. (21) It is too late, after facts have been proved and 
recorded by others, to claim priority unless one can point to unmis- 
takable evidence, in print, as proof that the facts have been demon- 
strated and duly reported. In our preliminary report (22) Dr. 
Finlay has been given due credit for priority in advancing and advo- 
cating the mosquito theory. Nothing more is due to him. He 
states (21) that he had "many years ago discovered that yellow 
fever was transmitted by mosquitoes," when in reality he simply 



YELLOW FEVER. 181 

assumes that to be the case, and the facts recorded by him do not 
sustain his claim. (23) He further states (21) that his own work had 
been singularly misrepresented before the American public, and 
that " among the facts and conjectures which are attributed to the 
recent investigators there is scarcely one which had not been asserted, 
demonstrated, or suggested by me, as the result of my personal experi- 
ments and observations." One can only express admiration for this 
eminent scientist's persistent adherence to his theory, but the unbiased 
observer, after a perusal of his numerous writings, must agree with 
us that while he asserted and suggested everything that intelligent 
reasoning and profound knowledge could suggest, he failed to pro- 
duce a single case of the disease. Our results have been confirmed 
by Guiteras with eight cases and three deaths; (24) Dr. Finlay's 
assumed results have never been confirmed by a single investigator. 
In our " Additional note" (25) we report among other instances one 
in which the bites of 14 insects, applied 4 days after contamination, 
failed to infect, and the 7 remaining alive failed also to infect 11 days 
after contamination, but on the seventeenth day following contamina- 
tion the bites of 4 of the same insects produced an attack of yellow 
fever in "the same individual." During the whole of this time these 
insects had been kept in a heated room at an average temperature of 
82° F. If, as is claimed by Finlay, (26) protection is conferred by 
one or two bites of "recently contaminated" — two to five days (19) — 
mosquitoes, this individual, who had received 21 bites from recently 
contaminated insects, should have been able to resist the bites of 4 
of the same insects 6 and 13 days later. Should one accept Finlay's 
extension of the incubation period to 22 days infection might then 
be erroneously attributed to the bites inflicted 13 days before the 
onset of fever. 

The Army board worked on an entirely different hypothesis from 
Finlay, who believed that the infecting agent was retained on the 
biting parts of the mosquito, that infection was direct, and no interval 
was necessar} 7 . The board worked on the hypothesis that the specific 
agent of yellow fever was probably one of that group of strict parasites 
that in nature necessarily pass through two distinct and alternating 
cycles of development, one within the body of a vertebrate, the other 
within a blood-sucking invertebrate host. Finlay believed that the 
bite of a single insect would confer a mild infection and multiple 
bites a severe one. In my own case, produced by the bite of a single 
insect, a fatal result was looked for during several days. Dr. Lazear 
was bitten by a single insect and died. (27) I became so firmly con- 
vinced that the severity of an attack depended on the susceptibility 
of an individual rather than on the number of bites sustained, that 
on October 9, 1901, at Habana, I purposely applied to a nonimmune 
8 mosquitoes (all I had) that had been contaminated 18 days before. 
The attack that followed was a mild one; the temperature never 
reached 103° F., and dropped to normal on the evening of the fourth 
day. (27) 

The original theory of Finlay has been variously modified by him 
from time to time to meet possible contingencies. He now evidently 
inclines to the belief that development of the germ takes place in the 
salivary glands of the infected mosquito. (21) 



182 YELLOW FEVER. 

Table 3. — Positive mosquito inoculations of the Army commission. 



No. 


Character of at- 
tack and number 
of patients 
bitten. 


Days of dis- 
ease. 


Period 
in mos- 
quito. 


Num- 
ber of 
mos- 
quitoes 
used 
(room 
temper- 
ature). 


Date of appli- 
cation of mos- 
quitoes. 


Incubation. 


Character of 
attack. 




f Severe, 1 


Second 

First 

Second 

do 

do.... 


Days. 
12 
6 
4 
2 

2-16 

2-15 

1-19 

2-21 

17 

f 18 

\ 22 

24 

19 

20 

f 21 

\ 25 

27 

1-24 

/ 10- 5 

i 12 

4- 8 

17. 

39 

51 

57 

16 

1-53 

3-34 

18 


1 
4 

1 • 

1 4 

I : 
1- 

14 
13 
12 
12 
13 

} * 

8 


Aug. 27,1900 

Aug. 31,1900 

Dec. 5, 1900 

Dec. 8, 1900 
Dec. 9, 1900 
Dec. 11,1900 

Dec. 21,1900 

Dec. 30,1900 
Jan. 19,1901 
Jan. 31,1901 
Feb. 6, 1901 
Feb. 7, 1901 

Sept. 16,1901 

Oct. 9, 1901 


3 days 7 hours 

6 days 






iMild, l 




1 




Severe. 




[Mild, 1 

f Fatal, 2 






JMild, 8 


First and 
second. 

First, sec- 
ond, and 
third. 

Second 

do... 




2 




Moderate. 




[Fatal, 2 


3 days 10 hours . . . 

5 days 17 hours . . . 
3 days 12 hours... 
3 days 20 hours . . . 

3 days 23 hours... 

do 

4 days 




3 








[Mild, 1 


Third 

do... . 






("Fatal, 1 






1 Severe, 2 


Second and 

third. 

Third 

Second 

Third 

Second and 

third. 

Third 

Second 

First 

do 

do 

Third 

do 

do 

Second 

Third 

Second 

do 




4 


[Moderate, 1 

Fatal, 1 


Mild. 
Do. 




f....do 






1 Severe, 2 


Moderate; re- 


6 


(.Moderate, 1 

("Severe, 1 


< lapse on third 
[ day. 


7 

8 
9 


< Well marked, 2.. 

[Mild, 1 

do 

Well marked, 1.. 

do 

do. 

Fatal, 1 


Pronounced. 
Mild. 


10 
11 
12 


3 days 3 hours 

3 days 6 hours 

2 days 22 hours... 

3 days 


Mild. 
Do. 




/ do 




13 


t-.-.do 

Severe, 1 




14 


3 days 8 hours 


Mild. 



•82° F. 



A complete proof or disproof of his claim of positive results for his 
recorded inoculations could easily be obtained by means of a series 
of innocent experiments. It is interesting to note that at the very 
time when this distinguished authority is in position to confirm the 
results of his first inoculations, if they are susceptible of confirmation, 
he takes the ground that inoculation experiments on human beings 
in Cuba must be strictly forbidden. (21) 

Table 4. — Positive mosquito inoculations oj Dr. Guiteras. 



No. 


Character of at- 
tack and num- 
ber patients 
bitten. 


Day of dis- 
disease. 


Period in 
mosquito. 


Number 
of mos- 
quitoes 
used. 


Date of 
applica- 
tion of 
mosqui- 
toes. 


Incubation. 


Character of attack. 


1 

9 


Severe 

do 


First 

Third 

...do 

...do 


Days. 
26 
19 
19 
20 
24 
24 
24 
34 


1 
4 
4 
3 
1 
2 
3 
2 


1901 
Feb. 23 
Aug. 8 

...do 

Aug. 9 
Aug. 13 
Aug. 14 

...do 

Aug. 22 


3 days, 10 hours... 

4 days, 5 hours 

3 days, 3 hours 

5 days, 3 hours 

3 days, 19 hours... 
3 days, 21 hours... 
5 days, 21 hours... 
3 days 


Pronounced. 
Fatal. 


3 


do 

do 


Mild. 
Fatal. 


5 

6 


do 

..do 


...do 

..do 


Mild. 
Fatal. 


7 


..do. 


...do 


Moderately severe. 


8 


do 


...do 











1 Case 4 had been bitten with negative result 10 days previously by 4 mosquitoes 5 days after they had 
bitten a fatal case in the third day of the disease. See Case 33 of Guiteras's table, Amer.Med., Nov. 23, 
1901, p. 811. 



YELLOW FEVEK. 183 

It is unfortunate that Dr. Finlay in his numerous contributions to 
this subject very seldom gives exact references that would enable one 
to compare his more recent assertions with his former statements. 
In regard to his expressed opinion that the great merit of our work 
consists in our having accurately defined the danger line, beyond 
which there is a risk of producing severe or fatal experimental cases 
when nonimmunes are inoculated with mosquitoes whose contamina- 
tion is more than 10 days old (21), I desire to record my belief, based 
on experimental observation and on the results obtained by Guiteras, 
that it is impossible to confer protection or to produce infection of 
any grade, with an insect that has been contaminated less than a 
week, and that inoculations with a mosquito contaminated for a 
shorter period will be absolutely devoid of result. The accompany- 
ing tables, compiled from our and Guiteras's cases, afford a substantial 
basis for the assertion. I deem it a duty to the service to which I 
belong, to my dead colleagues (Reed and Lazear) and to the profes- 
sion, to state the facts plainly and clearly. I do not expect that this 
paper will remain unanswered; nevertheless, I shall decline to engage 
in controversy and leave the final determination to those who are 
competent to judge, after they have carefully perused the publica- 
tions herein referred to. 

The mosquito theory has been practically demonstrated by the 
Army commission and Dr. Guiteras in two series comprising 22 cases 
in all. The noncommunicabihty of the disease by means of fomites 
has been a matter of common observation in certain localities, and 
has also been demonstrated practically by our own experiments and 
those of Havard and his associates. Yellow fever, therefore, is not 
a filth disease, in the strict sense of the term, and filthy accumula- 
tions are dangerous in this connection only when accompanied by 
sufficient moisture to breed mosquitoes under favorable conditions 
of temperature. Under such conditions standing water is a source 
of danger, within dwellings or without, and whether dirty or clean, 
unless it be kept covered or is changed every few days. Yellow fever 
is a preventable disease; quarantine, if effective, will exclude it, but 
if the quarantine be evaded and cases gain entrance to a city the 
disease can be absolutely controlled and finally exterminated by 
measures directed against the mosquito alone. 

Carter (7) has well shown (8) that first cases are not dangerous 
until after the lapse of a number of days, for, in his experience, persons 
in direct contact with them for a few days only never developed the 
disease after being placed in quarantine. This applies only to the 
first cases occurring in a town or neighborhood. He found that 
secondary cases did not appear until the expiration of a number of 
days, varying from 11 J to 29, the average being 18. This interval 
represents the time necessary for the mosquito, after biting a 
patient, to become capable of infecting, plus the period of incubation 
in the person bitten. 

The greatest obstacle to the control of this disease is the failure to 
recognize the first cases when they are not accompanied by black 
vomit. Some of these cases are so mild in character that no physi- 
cian would dare to pronounce them yellow fever unless he knew the 
disease to be ■ prevailing at the time. Susceptible persons visiting 
the house or living in adjoining houses would be bitten and develop 
the disease in near or distant localities several weeks later, forming 



184 YELLOW FEVER. 

secondary foci of infection. From these secondary foci tertiary foci 
would in time develop. The diagnosis of bilious remittent fever, 
dengue, etc., would serve to cover the earlier cases until the appear- 
ance of black vomit, by which time the infection would have become 
more or less widely disseminated. Such is the history of many 
outbreaks. 

The number of mosquitoes in infested districts can always be 
appreciably diminished by giving attention to surface drainage and 
the removal of standing water, no matter how small the quantity or 
how pure the quality may be. Rain gutters and conduits on build- 
ings should be kept clear and free; cisterns, wells, flush tanks, and 
other permanent receptacles for water should be kept tightly cov- 
ered or securely screened; privies and cesspools should be cared for; 
air vents to cisterns and wells protected by screens, and water should 
never be permitted to stand in any vessel or receptacle within a 
building longer than three or four days. Ditches and open drains 
containing water should be frequently flushed; old cans, crockery, 
etc., should be removed from the vicinity of dwellings; pools or 
ponds should be stocked with fish and deepened at the margins or 
treated with petroleum. As the stegomyia is largely a house-dwelling 
and a house-breeding insect, these and other similar measures will 
surely diminish their number and add to the general comfort and 
protection. In places exposed to yellow-fever infection all fever 
patients should be protected, night and day, from the bites of mos- 
quitoes by the use of netting and wire screens. Strict quarantine 
measures, local and general, with the isolation of patients and exten- 
sive and thorough fumigation of the localities where they are found 
will insure suppression of the disease wherever it may appear. 

In the suppression or control of yellow fever disinfection, apart from 
fumigation, is a waste of time and money. Natural yellow fever is 
transmitted by the mosquito, and always and only by the mosquito. 
The harmlessness of fomites has been fully demonstrated by our 
experiments in 1900 and 1901, in which three young Americans slept 
for 20 consecutive nights in a room garnished with articles soiled with 
black vomit, bloody fecal discharges and urine from fatal and other 
cases of yellow fever. Three and four large boxes were packed and 
unpacked with these articles night and morning by these nonimmunes, 
who suffered no disturbance of health from these exposures. The 
room was 20 feet by 14 feet, double walled, tightly ceiled, heated to 
above 90° F. and dark. Water was always present to keep the atmos- 
phere moist. Two other nonimmunes then occupied the room for 20 
nights while additional articles of bedding and clothing were added. 
They slept in the garments and between the sheets that had covered 
cases of yellow fever, some of which were fatal. The result of this 
second exposure was nil. A third attempt was then made with two 
additional nonimmunes equally without success.* Not the slightest 
indisposition followed close and intimate contact with this repulsive 
material in any case. Temperatures and pulse rates were recorded 
at regular and frequent intervals. Four of these seven nonimmunes 
were subsequently infected by blood injections and by means of 
infected mosquitoes. A fifth resisted the mosquito once (28) and 
declined further attempts at inoculation. 

Yellow fever has been eradicated from Habana, one of its endemic 
homes, by the institution of measures directed against the mosquito, 



YELLOW FEVER. 185 

after extreme cleanliness and energetic disinfection had proved a 
dismal failure. Several cases subsequently imported into that city 
have been handled with impunity by guarding the patients against 
the bites of those insects. A small outbreak in Santiago de las Vegas 
in 1901 was promptly suppressed by Col. Gorgas by the use of mean 
directed only against the mosquito. On those who decline to accept 
such evidence must rest the burden of proving that the disease is 
transmitted in some other way before their position can be sustained. 

REFERENCES. 

(1) Medical Inquiries and Observations, Benjamin Rush, M. D., Philadelphia, 1805, 
vol. iv., pp. 10, 77, 175. 

(2) An Essay on Yellow Fever, by B. B. Strobel, M. D., Charleston, S. C, 1840, p. 
162. 

(3) Report of Sanitary Commission of New Orleans on the Epidemic of Yellow Fever 
of 1853, New Orleans, 1854, vol. i, pp. 266, 278, 540. 

(4) The Epidemics of New Orleans, by Bennett Dowler, New Orleans, 1854, p. 44. 

(5) La Roche on Yellow Fever, Philadelphia, 1855, vol. i, pp. 67, 77, 79. 

(6) See footnote 2, p. 87, citing from the London Medical Gazette for August, 1839. 

(7) New Orleans Med. and Surg. Jour.. May, 1900. 

(8) Medical Record, N. Y., June 15, 1901. 

(9) Anales de la Academia de Ciencias Medicas de la Habana, Havana, xxvii, 
1890-91. p. 501. (Finlay.) 

(10) Original Article — republished in English in the Revista de la Asociacion 
Medico-Farmaceutica, Havana, Cuba, Jan. and Feb., 1902. (Finlay.) 

(11) Finlay: Ibid., pp. 362 and 369; also Edinburgh Med. Jour., Oct., 1894, p. 334. 

(12) Proceedings of the International Congress of Hygiene and Demography, Buda- 
pest, 1894, p. 702. 

(13) Edinburgh Med. Jour., vol. xli, 1 pp. 523 to 526. 

(14) Finlay: Amer. Jour. Med. Sci., n. s., vol. xcii, 1886, pp. 402, 403. 

(15) Footnote to p. 369, Revista de la Asociacion Medico-Farmaceutica, Havana, 
Feb., 1902. 

(16) Medical Record, N. Y., Feb. 9, 1901, p. 203. 

(17) The Journal A. M. A., April 13, 1901, p. 1041. 

(18) Ibid., Feb. 16, 1901, p. 439; 3d conclusion. 

(19) Medical Record, Aug. 31, 1901, p. 344. 

(20) Case 8 of Dr. Guiteras' series, Amer. Med., Nov. 23, 1901. 

(21) See reprint, p. 8, on "Method of Stamping Out Yellow Fever, Etc.," by Dr. 
Charles Finlay, M. D., Conference of State and Provincial Boards of Health, New 
Haven, Conn., Oct., 20, 1902, and Medicine, Detroit, March, 1903, pp. 175, 179. 

(22) Phila. Med. Jour., Oct. 27, 1900. 

(23) Sternberg, Amer. Jour. Med. Sci., new series, vol. cii, 1891, p. 627, and Nuttall, 
Johns Hopkins Hosp. Reports, vol. viiii, 1899-1900. p. 27. 

(24) Amer. Med., Nov. 23, 1901. 

(25) The Journal A. M. A., Feb. 16, 1901. 

(26) Finlay: Edinburgh Med. Jour., Oct., 1894, p. 335. 

(27) The Etiology of Yellow Fever, Amer. Med., Feb. 22, 1902; Case 2. 

(28) Case 22, Table 2. 



Chapter 2. 

REMARKS ON EPIDEMIC OF YELLOW FEVER IN BALTIMORE. 1 

By James Carroll, M. D., surgeon United States Army, Washington, D. C. 

Mr. President and gentlemen of the alumni association: 
Instead of a strictly technical theme, I have chosen one that may 
be of more general interest, and which formerly demanded the atten- 
tion of two of the most brilliant minds among the early teachers of 
the university. 

Dr. Nathaniel Potter, a former pupil of Dr. Benjamin Rush, and 
afterwards the first professor of theory and practice of medicine in 
the university, held in 1793 that yellow fever was not- contagious, 
and he communicated this opinion to Dr. Rush in writing. According 
to his own statement, he believed that he was the only person in 
America who held that opinion, and in 1795 he prepared to defend 
his belief in an inaugural thesis to be read at the next commence- 
ment of the University of Pennsylvania, of which he was a student. 
He was dissuaded by Dr. Wistar on the grounds of propriety and 
expediency. Dr. Potter states that in 1797 Push's contention that 
the disease was contagious was first publicly attacked by Dr. John 
B. Davidge, one of the founders and the first professor of surgery 
and obstetrics in this school, whose paper was published in the 
Federal Gazette, of Baltimore, on the 30th day of November, 1797. 
Dr. Davidge subsequently enlarged his paper and embodied it in a 
volume entitled "Physical Sketches," published in Baltimore in 1814. 
On account of the importance of this city as a seaport, in almost 
constant intercourse with the West Indies, yellow fever must have 
been introduced a great many times, yet the only important epi- 
demic outbreaks of the disease took place in 1794, 1797, 1800, and 
1819. It is notable that all the outbreaks began at Locust Point, 
or about the docks and wharves, and they can be traced directly or 
indirectly to the shipping. The relatively high ground upon which 
the city stood, and the distance from the city proper to the wharves 
and shipping, explain why the interurban residents suffered .but little, 
while those living upon the poorly drained, low-lying districts near 
the river were compelled on such occasions to flee for safety. 

It can be easily shown that yellow fever was frequently confounded 
with malaria; indeed, it was strongly contended that the two dis- 
eases were one and the same, the difference being only in the degree 
of intensity. Then, while many contended that the disease was 
imported, and though their contentions could be supported by sworn 
testimony, there were others among the leaders and teachers in the 
profession who held, with Push, that since the infection was most 
prevalent in poorly drained localities, the water and decomposing 
vegetable matter must be necessary for the generation of the poison, 
which was manifestly conveyed through the atmosphere. The 

1 The Hospital Bulletin, University of Maryland, Feb. 15, 1905. 
186 



YELLOW FEVER. 187 

general restriction of the disease to the localities described, the 
observation that many persons who visited those localities for only a 
few hours became infected, while in other localities no infection took 
place, even among those who were intimately associated with the 
patients, proved the disease to be one of locality. With the observa- 
tion that if the wind blew strongly from the direction of the infected 
locality toward the city, that within a few days the disease also ex- 
tended toward the city, it was concluded, with reason, that the poison 
must exist in the atmosphere, that it was transported by the winds, 
and that infection could only result from the inhalation of this poison, 
which was believed to be gaseous in nature. This agreed with Syd- 
enham's theory of the epidemic constitution of the atmosphere, which 
was supported by Rush and his pupils, and which then seemed to 
offer the only explanation of the recorded observations of centuries. 
If we admit the mosquito as the sole carrier of the disease, we will 
be prepared to acknowledge that their observations were, in the 
main points, strictly accurate; that their reasoning was logical, and 
the deductions fully justified by the premises. It then becomes very 
easy to understand how the disease became one of lowly situated 
and poorly drained localities; how it was transmitted by the atmos- 
phere; how it failed to spread in certain locations; and how it dis- 
appeared upon the appearance of a heavy frost. The observation 
was actually recorded by a Baltimore physician that during the 
epidemic mosquitoes became an intolerable pest, while but a short 
time before no mosquitoes were observed. 

How beautifully this observation agrees with our present knowl- 
edge that the yellow-fever-carrying mosquitoes can be conveyed on 
vessels ; that in the warmer season of the year they will multiply on 
shore, gradually extending from house to house, breeding in and 
about the dwellings (for they are domesticated insects), and that 
they become infected only after feeding upon a patient. The impor- 
tation of the mosquito explains the appearance of this insect in places 
where it usually does not exist; it explains the occurrence of the 
earlier cases amon^ persons who either visited the vessels or wharves 
or docks, or who lived in the vicinity of them. It also explains why 
favorable localities were visited by the infection only, as a rule, when 
they received shipping; while localities equally favorable to the 
infection, but far from the shipping, remained free from it. Of course, 
the absence of the proper mosquito explains the failure of the disease 
to spread to any extent in the city proper. This stood upon ground 
that was high and dry, and it was at that time some distance from 
Fell's Point, the location of Sugar House Wharf where many of the 
vessels from the West Indies probably made their landing. Assum- 
ing that at the Sugar House Wharf cargoes of sugar were unloaded, 
we are reminded that sugar is a favorite food for the yellow-fever 
mosquito, and that it can subsist on this and water alone for months. 
Now Sugar House Wharf was at Fell's Point, and most of the out- 
breaks began at Fell's Point, where, presumably, the largest number 
of mosquitoes was imported. 

During the epidemic of 1794, 360 deaths were recorded. Dr. 
Drysdale reported x that he saw his first case just before death on the 
7th of August, at Bowley's Wharf, in the town, and on the 14th, 

1 The Philadelphia Medical Museum, 1805, 1 26. Letters written by Dr. Drysdale to Dr. Rush. 



188 YELLOW FEVER. 

20th, 22d, and 23d of the same month he saw Rye additional cases 
at the same part of the wharf. There were also at the same place 
some other cases which did not come under his care. Dr. Drysdale 
states that there was considerable sickness at Fell's Point after the 
death of his first case, and many deaths had occurred suddenly, 
or after a short indisposition. An investigation was made by three 
of the most respectable physicians, who reported that the prevailing 
fever was the common epidemic of the season which visited the 
Southern and Middle States annually, viz, the bilious remittent 
fever. The number of cases now rapidly increased, so that by Sep- 
tember 25, in about seven weeks, five physicians were attacked and 
two of them died. The cases had become so numerous that Dr. 
Coulter visited and prescribed for more than 120 persons daily. By 
the end of the month many families had sought refuge in the country. 
During this time the city remained unusually healthy, and although 
some persons infected at the Point died in the city proper, in that 
location the disease failed to spread. 

In his ninth letter of a series to Dr. Rush he states that yellow 
fever was first discovered at two points, remote from each other, viz, 
at Bowleys Wharf in the town, and at Fells Point. Many cases 
occurred throughout the town, but these originated either from com- 
munication with Bowleys Wharf or the Point, and the infection 
could be distinctly traced to one of those two places. Being puzzled 
to explain why the infection was confined to those two places, he 
found that the first cases on the Point were confined to houses 
whose cellars were filled with stagnant, putrid water, and he also 
found black, putrid, and offensive water beneath the stores in which 
the sick resided at Bowleys Wharf. Almost all those who were 
first affected were newcomers. Dr. Drysdale describes the Point 
as being low and flat; its streets generally not paved; its alleys 
filthy, and the ground around it marshy in many places. The 
frequent warm rains kept the noxious places constantly moist under 
a hot sun. We can easily recognize these as conditions favorable 
to the multiplication of mosquitoes, and the domestic habits of the 
stegomyia mosquito would tend to keep the infection rather closely 
confined to these localities. He further makes the significant 
statement that remittents were present from a very early period. 
It is more than probable that many of these remittents were true 
yellow fever, because under the belief then prevailing, that these 
were simply the prevailing types of summer fever, they would not 
be reported. It is also probable that if occasional cases were known 
to have been yellow fever, some physicians would have concealed 
them from the same motives that prevail to-day. He could discover 
no satisfactory evidence of the importation of the disease, though he 
states that the Triumph arrived at the wharf about the last of June, 
with almost all the crew indisposed, and previous to this there lay 
at the wharf a schooner whose captain had died on the voyage from 
the West Indies. The fact alone, however, that vessels from the 
West Indies came up to the wharf is sufficient to indicate to us 
the source from which the infection was received. The following 
sentence toward the end of the ninth letter is of extreme interest: 
"Locusts were not more numerous in the reign of Pharaoh than 
mosquitoes through the last few months; yet these insects were very 
rare only a few years past, when a far greater portion of Baltimore 



YELLOW FEVER. 189 

was a marsh." With wonderful acuteness of observation he remarks 
that some families at the Point avoided yellow fever by carefully 
precluding all communication with the sick, and that vessels also 
preserved their crews in health by removing to a distance from the 
wharf and preventing the sailors from going ashore. As soon as one 
infected person came on board he quickly infected all or most of the 
crew. He instances one man who contracted the disease on shore 
and carried it on board the ship Plioenix, whose crew was healthy. 
These all became infected and 5 out of 12 died. As the result of 
these observations he very naturally concluded that in some instances 
the fever proved contagious. These, and other cases cited, are 
now so easily explained by the mosquito theory that we can not 
appreciate the perplexity of the problem as it formerly presented 
itself for solution. The most accurate and careful observation 
yielded results that were apparently contradictory. All honor to 
Dr. Drysdale, whose tenth and last letter of the series was written 
to Dr. Rush in December, 1794. 

Some further interesting references to this epidemic were published 
by Dr. John B. Davidge in 1798 and subsequently rewritten by him 
in a treatise on yellow fever, published in 1813. He makes the inter- 
esting statement that the yellow fever first appeared in the last of 
August, but the common bilious fever prevailed at Fells Point from 
June. A lady from Philadelphia was attacked with yellow fever, 
on Charles Street, and she had black vomit, but no other person in 
the family or neighborhood was attacked during the whole season. 
He noted that the disease extended in the direction of the prevailing 
winds, and that it was conveyed by a northeast wind all along 
Federal Hill and the west end of the basin. A considerable number 
of cases occurred in the city and many who had attended the launch- 
ing of a frigate (near the water, of course), subsequently suffered 
from yellow fever, and several of them died, but no single person in 
the city contracted the disease from them. 

Concerning the prevalence of yellow fever in Baltimore at that 
time (1798), Dr. Davidge writes: 

A physician in conversation the other day told me that he had met with the yellow 
fever in Baltimore ever since he had lived there, which is 15 or 20 years. It is vio- 
lating all obligations of decency and truth to say that it is of recent date. 

This statement was probably correct, for every importation of the 
disease is not necessarily followed by an epidemic. In Baltimore 
and other places where the mosquito, Stegomyia fasciata, is not 
normally present, an epidemic is not possible, after the introduction 
of any number of cases, provided the mosquito be absent. For the 
production of an epidemic the introduction of infected mosquitoes 
alone during the hot season may suffice, because the mosquitoes 
deposit their eggs, and in a week or 10 days another brood will have 
become mature. The insects of this new brood must bite a patient 
in the first three or four days of the attack in order that they may 
become infected. Should only one or two infected insects be brought 
in and should they die (as frequently happens) immediately after 
depositing their eggs, then the disease would appear only in the 
persons first bitten by them, and these would have passed beyond 
the infective period by the time the new brood had matured. Should 
the infected insects, however, have remained alive, and should they 
have bitten other persons, at intervals of a few days in succession, 



190 YELLOW FEVER. 

these persons would be in the proper stage of the disease at the 
maturing of the new brood to enable them to become infected. 
When the proper mosquito has been previously introduced into a 
favorable locality in the proper season, or when the mosquito, 
Stegomyia fasciata, is naturally present, the introduction subsequently 
of a single case may produce an epidemic. The facts above stated 
will readily explain the frequently reported appearance of sporadic 
cases without the occurrence of secondary ones. 

We can now see that the immunity against the disease enjoyed by 
the city proper evidently depended upon its high and dry location, 
which rendered the conditions unfavorable for the multiplication of 
the mosquitos that were imported. In this regard Baltimore was 
more fortunate than Philadelphia, which was lower and contained 
more standing water. Hence, the mosquitos were more abundant 
and the disease spread uniformly. This led Dr. Rush to contend that 
the disease must be contagious, while Dr. Davidge held that the con- 
tagion was local, and existed only in the air of certain spots, from 
where it might be wafted by the winds in any direction. Dr. Davidge 
asserted (p. 84) that they had the most stubborn and irrefragable 
proofs, in those cases occurring about the wharves and at Fells Point, 
that the disease was incapable of supporting itself. When these cases 
were removed up into the city their virulence died with them, those 
who died; and, he writes, "from those who recovered, all mischief and 
supposed contagion evanesced into empty air, which bore it to the 
pages of medical writers, and not to the bodies of healthy attendants. 
This was the result in 1794 and 1797." 

The importance of this observation can hardly be overestimated; 
it shows the sagacity and care with which the epidemic was studied 
by these devoted men. Dr. Davidge learned the truth, and that 
truth unfortunately still remains to-day a hidden mystery to many 
of our practitioners, notwithstanding the recent absolute demonstra- 
tion of it beyond a shadow of a doubt. 

In connection with the now known mosquito propagation of the 
disease, an observation recorded by Dr. Nathaniel Potter 1 in this 
outbreak of 1797 deserves mention. He tells us that previous to the 
17th of September the fever had been confined to certain places and 
to such as had breathed the air evolved from them; on that day a 
strong southeast wind wafted the effluvia in a northwest direction 
and diffused it among the inhabitants of the upper parts of Fred- 
erick, Gay, South, and Calvert Streets, who became immediately 
implicated in all the horrors of the fever. 

In 1800 there appeared the severest outbreak the city has known. 
The mortality from yellow fever is recorded to have been 1,197, or 
about 1 in 50 of the population of 60,000. Again the disease began 
at Fells Point, on the borders of the cove, which extended from 
Jones Falls to the interior. The faculty of medicine of the city, after 
investigation, reported to the mayor that in their belief the disease 
was not imported-, but originated in the cove from the stagnation and 
putrefaction of filth under a summer's sun. The first two cases ap- 
peared on the 2d of May, 2 another on the 8th of June, one on the 
9th, 10th, and 13th; then from the 22d they became more numerous. 

i Memoir on Contagion, by Nathaniel Potter, M. D., Baltimore, 1818, p. 20. 
2 Medical Repository, New York, 1801, vol. IV, p. 351. 



YELLOW FEVER. 191 

It is unfortunate that we have no detailed description of this epi- 
demic, the most disastrous the city has ever experienced. 

A few cases are reported for the years 1802-1805. 

The next important outbreak took place in 1819 following the 
arrival of an infected ship from Habana. 1 In a letter to the editors 
of the Medical Repository, Dr. Pierre Chatard, 2 of Baltimore, writing 
October 19, cites the first cases as follows: The fever commenced 
raging at Fells Point in the beginning of July, and never ceased there 
until the end of October. It appeared also at Smith's Dock toward 
the end of July, carrying off five persons whose names are given, and 
others. The persons named had countinghouses on the dock or in 
the vicinity. No other cases appeared at the dock for two months, 
at the end of which time two more appeared. Dr. Chatard attributes 
the absence of cases during this time to the great quantity of lime 
that had been strewn on the ground by order of the mayor. The lime 
was again applied and the cases ceased. At Fells Point the disease 
raged for three months before it subsided. The greater part of the 
population retired to the healthier portions of the city, and many of 
them sickened and died there, but none of their friends or relatives 
suffered in consequence. We are told by Dr. Chatard that the 
epidemic focus on the Point never exceeded seven or eight thousand 
square feet. This information he regarded as precious because it 
demonstrated the noncontagiousness of the disease and the value of a 
local quarantine. 

Among the most interesting records of this epidemic are the letters 
and other documents published by authority of the mayor in 1820. 
These contain the actual opinion and experiences of the physicians, 
and they show a remarkable unanimity in the belief among the Balti- 
more physicians that the disease was noncontagious. The persist- 
ency with which the infection originated and remained in the vicinity 
of shipping, wharves, etc., is generally commented on. Dr. Clendinen 
reports that his first cases were located at the southeast corner of 
Fells Point, and several of them appeared among foreigners on board 
the shipping, persons who had been healthy previous to their arrival. 
This invasion by the disease of healthy ships tied up to the wharves 
appeared to be indisputable evidence of the poisoned condition of the 
atmosphere. Of course it is hardly necessary to say here that these 
vessels were simply invaded by infected mosquitoes. Dr. Clendinen 
was a resident of the Point, and he states that his family had suffered 
from the disease and he had lost a student, an assistant physician, 
and some of his best friends. Dr. Samuel B. Martin, after enumerat- 
ing 34 of his earlier cases, with their location about the wharves and 
shipyards, states: 

These will suffice, I think, to show the course the disease took in its commencement, 
traveling regularly along the course of the water and infecting the streets in the vicinity 
thereof. My most violent cases were near the water's edge or contracted there. 

No mention of this epidemic would be complete without a reference 
to the little book by Dr. David M. Reese, entitled "Observations on 
the Epidemic of 1819," a book which every one interested in the 
subject should read. According to him, some persons attributed the 
epidemic to the arrival of the schooner Adventure from the West 

1 Carpenter on Yellow Fever, New Orleans, 1844, p. 18. 

2 Medical Repository, New York, vol. 20, 1820, p. 261, 



192 YELLOW FEVER. 

Indies, laden with coffee, while others looked with suspicious eyes 
upon the schooner Proserpine laden with hides and coffee. Both 
vessels were ordered to the quarantine ground, but were soon per- 
mitted to return because, after a reexamination by the health officer, 
their cargoes were found to be in a sound condition. 

Referring to the time when 1,016 cases had been reported by the 
physicians, Dr. Reese states that of all of these only 12 were supposed to 
have originated in the city. He calls attention to the remarkable 
fact that, in almost every instance where a person visited the Point 
at night the contracted they disease, while those who were there only 
in the daytime escaped with impunity. He further remarks that 
those of the Baltimore physicians who became infected suffered in 
consequence of paying a visit by night to the source of infection, or 
to the vicinity where the cause existed. Several physicians who had 
attended patients in the daytime in the very center of the infection, 
and through the whole course of the fever remained exempt until by 
visiting the district once in the night they contracted the disease. 
This accords perfectly with the mosquito theory and with the twilight 
habits of stegomyiafasciata, the particular mosquito now known to be 
concerned in the transmission of the disease. It is also in accord with 
the experience of the American troops near Habana. Soldiers who 
visited the city only between the hours of 9 a. m. and 4 p. m. remained 
free from the disease, while among those who became infected there 
were but few who did not acknowledge having spent a night or a part of 
anight out of the barrack. Let us now consider what evidence, if any, 
collected by these closely observant Baltimore physicians could be 
used to support the mosquito theory to-day. Firstly, they recorded 
the presence of an unusually large number of mosquitoes; secondly, 
they observed that the infection was localized in the low, wet districts 
near the river and shipping ; thirdly, they noted that the infection was 
contracted mostly at night ; fourthly, they showed that in the higher 
and drier ground of the city proper the disease was absolutely non- 
contagious; fifthly, they reported that the disease traveled in the 
direction of the prevailing winds, when these were strong and blew in 
one direction ; and, sixthly, they were familiar with the fact that yel- 
low fever was most apt to prevail when the mean temperature was 
high, and they knew perfectly well that the disease was stamped out 
by the frost. To this we can add nothing more than the direct 
implication of the mosquito. 

Of course, a mistake was made in the failure to recognize the 
imported nature of the disease, and strong protests were written 
against the quarantine methods then in force against Baltimore by 
Philadelphia, Wilmington, and other places. These quarantines 
were established in the belief that the disease was contagious. The 
Baltimore physicians, having the strongest proofs that it was not, 
felt that they were treated with undue severity. In a low-lying city 
like Philadelphia, where mosquitoes were numerous, there was justi- 
fication for the belief in contagion, so that, while both were partly 
wrong in their opinions, under the circumstances the method of 
quarantine was a justifiable and proper one to adopt for their safety. 
On the other hand, the lax quarantine system at Baltimore was a 
source of danger; still it was justifiable on the ground of the availa- 
ble evidence to show that yellow fever was not contagious and upon 
the belief then prevailing that all infectious fevers were the result 



YELLOW FEVER. 193 

of putrefaction. Hence, if a vessel were clean and her cargo in good 
condition, it was assumed that she could not harbor the seeds of the 
disease and she was permitted to come into dock and unload. 

In the management of the epidemic the wise policy was adopted of 
advising all persons to flee the infected location and seek a residence 
upon high ground without the range of the infection. This the major- 
ity did, many going to the country or remaining nearby, while some 
refused to leave their habitations, and these latter furnished the fuel 
for the continuance of the pestilence. This epidemic is said to have 
cost the city 350 lives. 

The kindly concern shown for the welfare of the destitute poor 
stands out brightly in the history of this outbreak. It became nec- 
essary to remove the healthy poor from Fell's Point and provide 
means of shelter and sustenance for them until it was safe for them 
to return. A committee was appointed who visited a Mr. Owen Dor- 
sey to solicit the use of a ropewalk owned by him. This was granted 
free of charge and the removal began. More room was soon needed, 
and a Mr. Christopher Chapman gave up another adjacent ropewalk, 
1,000 feet long, for the purpose. This was not sufficient and more 
than 100 tents and marquees were then pitched and filled. Over 
1,000 persons were received, made comfortable, and supplied with 
provisions and every necessity. The corporation appropriated 
$1,000, but this was returned, the donations of money and supplies 
being ample for all purposes. Xot withstanding the partial depopu- 
lation, business depression, failure of some of the leading commer- 
cial houses and one of the banks, over 84,000 in cash were contrib- 
uted and liberal donations of food, clothing, etc., poured into the 
warehouses designated to receive them. The neighboring farmers 
contributed flour, fruit, and vegetables as well as money, and George- 
town, D. O, contributed $700. A soup house was established at 
the encampment, and this supplied over 100 gallons of rich, whole- 
some soup daily. This enterprise was undertaken by three energetic 
gentlemen — Messrs. Stewart, Mosher, and Coale — and through vol- 
untary contributions of material and labor the total outlay required 
was only $10. The camp was maintained for 53 days, and when it 
was broken up, on the 25th day of October, each person was sup- 
plied with provisions for three days. There were only six deaths 
m the encampment and five additional in the hospital of persons 
who contracted the fever at the Point and were carried from the 
camp to the hospital for treatment. The sick among the poor were 
cared for at the hospital at the expense of the city. Food, luxuries, 
and stimulants were provided for distribution upon the order of any 
practicing physician. It is estimated that by these means several 
hundred lives were saved, and the record is one of which Baltimore 
should be proud. The mayor, Edward Johnson, was a man of 
Christian character, high courage, and strong determination. Dis- 
regarding protests, the mayor and many of the board of health visited 
the hospitals during the height of the epidemic, and by their example 
inspired others with confidence in the noncontagious nature of the 
disease. Dr. Reese wrote of him : 

Mr. Johnson is one of the few individuals with whom, when interest and duty are 
in opposite scales, the latter will ever predominate. 

After this disastrous epidemic a few cases occurred annually until 
1805, and perhaps later. 



79965°— S. Doc. 822, 61-3 1; 



194 YELLOW PEVEK. 

Ten cases are reported to have appeared at Fort McHenry in 1868, 
and the disease was believed to come from infected vessels in quaran- 
tine near by. It is probable, as has been stated by Dr. John Morris, 1 
that sporadic outbreaks were frequent at Fells Point until 1855. 
In this year Dr. Kemp, of the board of health, had the infected 
district drained and cleaned. It is said to have been free from the 
disease from then until 1876 (except during the suspension of com- 
merce during the Civil War), when a small outbreak ,of the fever 
undoubtedly appeared, though the cases were not officially reported. 2 

In this review of the epidemics at Baltimore, the literature of 
which is very scant, I have confined myself to a simple narration of 
the facts which seem to be of general interest, and I hope that some 
of you may be stimulated to read for yourselves the records written 
by men of this city, some of whom were teachers in our university 
and of whom you have every reason to be proud. 

i History of the Epidemic in Baltimore in 1876. Reports of American Public Health Association, Vol. 
IV, p. 244. 
2 Baltimore Physician and Surgeon, Vol. VI, No. 2, 1876, p. 37. 



Chapter 3. 

YELLOW FEVER: A POPULAR LECTURE. 1 

By James Carroll, M. D., assistant surgeon, United States Army. 

Yellow fever, or yellow jack, as it is more familiarly called, is so 
far as our knowledge goes, strictly an American plague or pestilence, 
and our earliest authentic accounts of this disease record its occur- 
rence in the West Indies at the middle of the seventeenth century. 
By one or two of the older writers it is reported to have been trans- 
ported there from Siam, but this seems unlikely, because yellow 
fever has never been shown to be an oriental disease. Before the 
time of Sydenham, oriental plague, typhus fever, smallpox, cholera, 
pernicious malaria, and yellow fever were all called putrid or pestilen- 
tial fevers; it was believed they were due to the same cause and 
that they were transmitted through the atmosphere as visitations 
from God. At that time the science of medicine stood upon such a 
low plane that the best English physicians were just beginning to 
learn that there were differences between measles and smallpox, 
typhoid fever or typhus fever, and malaria, etc. Harvey had only 
recently announced the circulation of the blood and Malpighi had 
followed him with a demonstration of the blood corpuscles in the 
smaller vessels (capillaries) uniting the arteries and veins. Peruvian 
bark, that blessing in malarial fevers, was barely known at the time 
when yellow fever first prevailed at Barbados, Jamaica, Santo 
Domingo, and Martinique, and later at Vera Cruz. In 1761 the 
disease was carried from Vera Cruz to Habana by the Spaniards, who 
lost 3,000 persons from it in that year alone, and in 1780, out of an 
army of 8,000, about 2,000 died of yellow fever within two months 
after landing at Habana. It is further reported that in 1794 there 
were over 1,600 \<ictims to yellow fever in the Spanish garrison and 
squadron at Habana. More recently, for the 10 years from 1870 to 
1879, inclusive, 11,746 deaths are recorded for the city of Habana 
from yellow fever alone. Spain paid dearly for the Pearl of the 
Antilles in both men and treasure, for, besides decimating her troops 
in Cuba, the disease followed them across the Atlantic and appeared 
in epidemic form in various cities of the Peninsula from time to time. 

The fearful mortality attendant upon this disease is well brought 
out in the accounts of some of these epidemics. For instance we are 
told by an English physician, Dr. O'Halloran, 2 who studied the epi- 
demic in Barcelona in 1821, that the general hospital received 830 
patients suffering from yellow fever, and of these no less than 749, or 
90 per cent, died. This keen observer contends the disease can not be 
contagious, but is due to some local infection of the atmosphere, and 
in support of his contention he cites numerous instances during the out- 

i Delivered at Galveston, Tex., Apr. 12, 1905, under the auspices of the University of Texas. Reprinted 
from American Medicine, Vol. IX, No. 22, pp. 907-915, June 3, 1905. 
2 Remarks on the Yellow Fever, bv Thomas O'Halloran, M. D., London, 1823. 

195 



196 YELLOW FEVER. 

break referred to, showing the disease was not and could not be di- 
rectly contagious, because during the epidemic thousands of persons 
fled from the city to the country, including those who had slept with, 
nursed, and been intimately associated with the sick, traveling in many 
instances in the same carts or carriages that had been used for the 
transportation of patients, and even the dead, and after carrying with 
them the personal effects of those who had died of the disease. Still, 
no other cases followed in the districts to which these people fled and 
the evidence appeared to be indisputable that the disease spread by 
contagion in certain localities within the city or its environs, and the 
conclusion was arrived at that the contagion could not exist in the 
country, but originated de novo in certain localities in the cities, as a 
result of peculiar atmospheric and local conditions. It was observed 
that the nuns of the general hospital who were thrown into frequent 
and direct contact with the sick escaped the disease, while in the con- 
valescent hospital the president, the head apothecary and the superin- 
tendent, none of whom had ever entered the rooms of the sick, and 
who had taken every precaution not to communicate with the sick 
nor with anything belonging to them, all fell ill. Of course, now 
that we know that natural or nonexperimental yellow fever can only 
be contracted through the bite of a contaminated mosquito, it is 
quite clear that the presence or absence of the disease in certain locali- 
ties means simply the presence or absence of contaminated mos- 
quitos. As we view the subject now, the yellow fever mosquito was 
brought to Spanish ports by vessels coming from Habana, and being 
a house mosquito, it multiplied in those cities during the warm season. 
It was then at hand to receive and transmit the infectious agent when- 
ever it encountered cases of the disease, and these were frequently im- 
ported. Upon the appearance of frost the mosquito went into hiber- 
nation and the epidemic promptly ceased. As the insect was an im- 
ported one it was not present in the country districts, consequently 
there was no extension of the disease from patients treated there, and 
in the cities the epidemic could only spread where the proper mos- 
quito chanced to be present. The introduction of the mosquito alone 
can have no ill effect unless it has previously bitten yellow fever pa- 
tients, and in like manner, sufferers from yellow fever are absolutely 
harmless to others unless they are bitten by the proper mosquito. 

As Dr. Howard, no doubt, told you last year, the female mosquito 
at certain periods in her existence experiences a physiologic need 
for blood. The hemoglobin of the blood seems necessary for the 
maturation of her ovums, and she will not deposit her eggs until she 
has obtained a meal of blood. The male insect can not transmit 
yellow fever, because, having no need for it, he never sucks blood, 
and while his proboscis will provide him with fruit juices, it will not 
penetrate the animal skin. The mysterious movements of the disease, 
passing from house to house, even at times when there had been no 
communication between the inhabitants; the remarkable immunity 
enjoyed by some groups of persons who were equally and fully as 
much exposed as others who were decimated by its ravages; these, 
as well as the peculiar way in which the infection clung to dwellings 
and ships, invested it with a mystery that puzzled physicians for 
centuries, and remained totally unexplained until the demonstration 
of the mosquito theory within the past five years. Even to-day, in 
our own country, where the results upon which it is based were first 



YELLOW FEVER. 197 

published, the mosquito theory of the transmission of yellow fever 
still has many opponents, and some of its supposed friends are very 
weak-kneed and seem still to be looking for evidence that would 
justify them in deserting it. It is painful to read, in one of our most 
prominent and influential daily newspapers, the letters emanating 
from a well-known writer upon the subject of }^ellow fever, who a 
few years ago was looked up to as an authority and wrote for 
standard professional works, but who is now damaging his own 
reputation and retarding progress by asserting that the mosquito is 
not the sole medium for the transmission of this disease. It does not 
seem to have occurred to this widely known and most interesting 
writer that the burden of proof rests upon him, and that he should 
either remain silent or be prepared to prove by actual demonstration 
that there is some foundation for his claim. I take the liberty here 
to suggest to the paper in whose interest this writer was sent to Cuba, 
that it could hardly invest a few hundred dollars more profitably than 
to enable this gentleman to furnish the necessary evidence in support 
of his statements, if such evidence is obtainable, as it certainly should 
be if his assertions are well founded. Who would think to-day of 
advancing the old theory that malarial infection is contracted in any 
other way than through the bite of the mosquito? No one who is 
familiar with modern ideas on parasitology would entertain the idea 
for a moment, and there is no more ground for assuming that yellow 
fever is transmitted in any other wa}^ than there was formerly for 
entertaining that opinion in regard to malaria. In your own State 
during the last two years you have had abundant evidence of the 
power of measures, based upon the mosquito theory alone, to suppress 
this disease, even when that theory met only half-hearted acceptance. 
Do not understand me as intending to reproach those hesitating 
nonbelievers who were so slow to move; on the contrary, I sympathize 
with them and with their refusal to conform their ideas to all the 
new theories that were being constantly advanced, then denied, con- 
tested, and recontested with every reappearance of the disease. 

But let us return again to the scenes enacted, and the conditions 
found, where the disease has prevailed in the past. Dr. O'Halloran, 
in summing up after studying the epidemic at Barcelona, calls atten- 
tion to the House of Charity, a clean, well-ventilated building in the 
noninfected part of the city, and which was occupied by more than 
1 ,100 persons during the height of the epidemic. These persons, men, 
women, and children, went out daily into various parts of the city, 
some visited the sick and entered the houses of the dying and the 
dead. Among ail this number, only 2 contracted the disease. These 
were treated in theSeminario Hospital, where 1 recovered and the other 
died. The one that recovered was at once returned to the House of 
Charity, where she mingled with the other inmates ; still none of them 
was affected. He then says: 

The foregoing is a true report, and may be regarded as an important one. Had the 
House of Charity been situated in the eastern extremity of Barcelona, or in Barceloneta, 
where the epidemic cause existed to a high degree, the destruction would have been 
in all probability great; but as the cause did not extend, or only in a very inferior 
degree, to that part of the city in which the House of Charity stands, the cause of the 
nonpropagation of the malady is easily accounted for. This case strongly tends to 
prove that the yellow fever will not multiply except where an epidemic cause exists 
in force; and it moreover proved that the disease is not contagious. 



198 YELLOW FEVEE. 

Further on, in speaking of the Casa Miserecordia, or House of Pity, 
he states : 

The building is low, but the apartments are spacious and well ventilated. It con- 
tained 150 girls during the rage of the epidemic. The nuns who teach them are 24 in 
number. They maintain themselves by washing, ironing, and other similar modes 
of occupation. They employ women to traverse the city from house to house to pro- 
cure needlework, etc. These women went to all parts of the city; they communicated 
indiscriminately with the inhabitants, and they were not affected by the disease, nor 
did the nuns or girls suffer by communicating with them. This is a singular fact, and 
a strong one. It appears strange that a disease which was said to have been imported 
from Habana into Barcelona, from Barcelona to Intosa, and from thence to Asco, 
Mequinenza, Malaga, etc., could not be introduced into the House of Pity through 
numerous channels of communication. 

Again, speaking of the House of Correction, a three-story stone 
building, in which were located 100 females during the epidemic 
season, he asserts : 

Nine of them were attacked with the reigning malady; 4 of them had been recently 
admitted as having committed some irregularity in sickly Barceloneta. They were 
all removed to the Seminario Hospital, where 4 died; the remaining 5, when cured, 
returned to the House of Correction; they communicated freely with the others, but 
no disease ensued. This house was visited daily by some of the female inhabitants of 
the city, who, through charity, brought eatables, etc., but without detriment to the 
inmates. 

Had this been a contagious malady, the persons who returned to 
the House of Correction after being cured in the Seminario Hospital, 
which was then the seat of pestilence and of death, and to which 
hundreds were sent to die, could scarcely have failed of communi- 
cating the disease to the numerous females who had intercourse with 
them at all hours of the day. 

Of 50 persons who were constantly employed burying the dead, 
only 2 died, although they communicated freely with the inhabitants 
of the city in the nighttime. 

Later he mentions the lazaretto called Marine, a mile to the east of 
Barcelona and within 150 yards of the sea. It was opened for the 
sick on August 7 ; 79 sick were admitted, of whom 58 died; 32 persons 
were employed in various duties of the establishment as doctors, 
friars, servants, and washerwomen, and not one of them took the 
disease. Of the above number, 6 were employed in burying the 
dead, and 3 in washing the bedding. After this establishment was 
broken up, 5 women remained in it, employed in washing the bedding 
of the Seminario Hospital, but without being affected by the disease. 

In his conclusions, he finally observes in discussing the epidemic : 

Its fatal and malignant nature in un ventilated places; the exemption of parts of the 
city from its influence, when no precautions were taken; the sickening of persons 
who observed the strictest seclusion; the sudden impression of contaminated air on 
persons recently from the country, without communication with the inhabitants of 
the city; the greater exemption of nurses and other attendants on the sick from the 
disease, than those who were simply exposed to the contaminated air of sickly houses; 
the almost absolute exemption of washers of bedding, clothes, etc., which had recently 
been used by the sick; the circumstance of the attendants in the hospitals and laza- 
rettos having generally escaped the impression of the malady; the impossibility of 
diffusing the disease in the country, where no epidemic cause existed; and, finally, 
the death of some hundreds of persons who communicated with Barcelona, and who 
sickened in the neighboring villages and country houses without a solitary instance 
of its affecting the most assiduous of its attendants, however circumstanced, are ascer- 
tained facts and convincing proofs of the noncontagious nature of the yellow fever. 

The evidence that Dr. O'Halloran offers in support of his conten- 
tion that yellow fever is not contagious is most conclusive. After 



YELLOW FEVER. 199 

reciting the appearances found upon dissecting the bodies of those 
who had died of the disease, he publishes a letter written by Dr. 
Salvador Campmany during the following year. Dr. Campmany was 
in charge of the Virreina Hospital at Barcelona during the outbreak 
of 1821, when, between September 1 and December 20, this hospital 
handled the bodies of no less than 8,649 persons dead of yellow fever. 
O'Halloran states that Dr. Campmany was at first of the belief that 
the disease was contagious, and when he began to take care of the 
sick he wore an oilcloth dress. The letter is so interesting that I 
shall give you the last paragraph verbatim. 

The above sketch does not afford grounds for argument as to the contagious or non- 
contagious nature of the disease. I shall only state that out of 30 persons of all descrip- 
tions who were destined to assist the sick not one took the disorder. The nurses con- 
tinually communicated with the sick. When delirious patients escaped from their 
beds the assistants had to take them on their shoulders and replace them in their 
respective quarters. On the opening of the bodies the anatomists, in my presence, 
involuntarily cut their fingers and hands, and not one was inoculated with the yellow 
fever. When the gravediggers carried the dead bodies to the church yard they had to 
handle them a great deal before throwing them into the pit,, and not one suffered in 
his health. In short, not an individual employed in the lazaretto either took the 
disorder or was infected by those who were sick of the yellow fever. 

One could scarcely desire more complete confirmation than this of 
the subsequent demonstration, almost 60 years later, by the army 
board, of the noninfectiousness of the clothing, bedding, and dejecta 
of yellow fever patients. 

These were the opinions in 1823 of an observer who had seen and 
himself suffered from yellow fever in the West Indies some years 
before. Others, however, who were equally qualified to observe, 
insisted, and advanced evidence to show, that the disease was 
imported and that it was contagious. In short, the same differences 
of opinion and the same dissensions among the highest authorities in 
regard to this disease prevailed then as before and since, even to the 
present day. O'Halloran states that the disease was not declared to 
be the American yellow fever until August 14, 1821; that in April a 
fleet of 52 vessels sailed from Habana for various Spanish ports, 20 of 
them for Barcelona. Cases of yellow fever occurred on some of these 
vessels after their arrival in Spain, but for commercial reasons every 
effort was made to conceal them and deny their real nature. Many 
of the sailors on the infected vessels were, of course, immune, and of 
those who were susceptible the larger number had suffered attacks 
during the voyage, so that while they were lying in the Spanish har- 
bors the first persons to become infected were those who visited the 
ships for the purpose of unloading, making repairs, etc. Some of 
these vessels lay at Barcelona early in June, and we are told that 
during this month ' 'the bilious remittent or gastric fever was common, 
and ultimately predominated in so high a degree as in a manner to 
supersede all other diseases; and that during the month of July the 
bilious remittent fever, with hemorrhagic affection, was common and 
obstinate." The following sentence, quoted verbatim, is of much 
interest to us at present : 

It is worthy of remark that during this month (July) the flies and mosquitoes were 
infinitely multiplied. 

How well this reminds us that the same unusual prevalence of 
mosquitoes during an epidemic of yellow fever has been noted by a 
number of American physicians, including Dr. Rush, at Philadelphia, 



200 YELLOW FEVER. 

in 1797 and 1805; Dr. Vaughan, at Wilmington, Del., in 1802; Dr. 
Weigh tmann, at St. Augustine, Fla., in 1839; Dr. Wood, at Center- 
ville, and Dr. Beyrenheidt, at Biloxi, Miss., as well as Dr. Barton, at 
Clinton, La., and Dr. Dowler, at New Orleans, all in 1853. What 
interest these observations add to the now well-known mosquito 
theory of the transmission of the disease, and how well do modern 
experiences and knowledge add confirmation to Sydenham's theory 
that certain diseases resulted from an "epidemic constitution of the 
atmosphere." 

I would like here to call your attention to some statements made 
by a well-known Galveston physician in 1876. Dr. Greensville 
Dowell, at that time a member of the Galveston Medical Society and 
professor of surgery in the Texas Medical College, wrote of yellow 
fever, of which he was a wonderfully close student, as follows:^ 

Its history shows that no ship, however filthy, can develop it while it remains out 
of its endemic or epidemic influence. No heat or moisture can alone produce it, or 
we would have it as often in the East Indies as in the West Indies, and if the conditions 
in the East Indies were the same as in the West Indies it would be introduced there, 
as well as in the West Indies, by ships. Hence there must be some cause, specific 
and sui generis, that produces it. This cause, I have assumed, is animalcular or fun- 
gotic, and partakes of the nature of the grasshoppers of Egypt and the western prai- 
ries, or the smut in cereals; but these are too small to be observed with any instruments 
we now have, and have so far eluded demonstration; but if we compare the effects of 
heat and cold on gnats and mosquitos with yellow fever, it will not be difficult to 
believe it is of the same nature, as it is controlled by the same natural laws. 1 

So far as I know, Dr. Greensville Dowell was the first even indi- 
rectly to incriminate the mosquito by pointing out the fact that it 
is governed by the same natural laws as yellow fever. And five 
years after, in 1881, Dr. Finlay enunciated his theory that the dis- 
ease was transmitted by the mosquito, but his theory was not proved 
until 19 years later. 

O'Halloran's observation that bilious remittent fevers prevailed for 
two months prior to the appearance of yellow fever has been dupli- 
cated in the United States hundreds of times, and we are forced to the 
conclusion that there must be some relationship between bilious remit- 
tent and yellow fever. O'Halloran thought that these bilious remit- 
tent fevers were of local origin and that they gradually merged into 
yellow fever. The same opinion has been held by many in our own 
country, but this has been offset by evidence, on the other hand, that 
bilious remittent fever was undoubtedly imported from the Tropics, 
and was simply a milder form of yellow fever. The truth is that 
practically all such cases were genuine yellow fever that were not 
recognized because of the absence of black vomit, which has been 
erroneously regarded as a necessary symptom. In the work of the 
Army commission 14 cases of experimental yellow fever were pro- 
duced by means of the mosquito, and some of them were severe, but 
black vomit was not present in a single instance. This led some 
persons to the conclusion that cases produced by only one or two 
mosquitos were necessarily mild, but the experience of Dr. Guiteras 
in August, 1901, proved the contrary. Out of seven cases that he 
produced by the bites of one or two mosquitoes, three died with 
black vomit. 

I have purposely cited from Dr. O'Halloran' s account of the epi- 
demic at Barcelona in order to show that other careful observers, 

i Yellow Fever and Malarial Diseases, by Greensville Dowell, M. D. Philadelphia: 1876, p. 13. 



YELLOW FEVER. 201 

working in other fields, have recorded the same observations and the 
same opinions as the older American physicians. 

The literature of yellow fever in the United States shows that in 
nearly every outbreak a number of cases, usually the first ones to 
occur, have escaped recognition. This has happened from the time 
of Rush until to-day, and has been due to (1) the comparative mild- 
ness of the cases, which led to the diagnosis of ''bilious remittent 
fever; 7 ' (2) the dread on the part of the physician attending these 
cases to assume the responsibility for diagnosing the first case of 
yellow fever, because, in the event that black vomit did not super- 
vene, the correctness of the diagnosis would be called into question, 
and the physician would be branded an enemy to the community. 
The Eleventh Annual Report of the Florida State Board of Health, 
published in 1900, furnishes an admirable illustration wherein it is 
shown that in the outbreak at Key West in August, 1899, there were 
already 11 cases unrecognized in the town before a single one was 
correctly diagnosed. Is it any wonder, then, that under such cir- 
cumstances the disease was able to gain a firm foothold ? The occur- 
rence of a number of cases of the so-called "bilious remittent fever," 
of short duration, should always excite suspicion, for such cases, 
when found in groups, are almost invariably cases of genuine yellow 
fever. At the present day nothing less than the absolute demonstra- 
tion by an experienced observer of the presence in the blood of 
malarial parasites or spirillums would justify any other diagnosis 
than yellow fever; and even if they were shown to be cases of malarial 
or relapsing fever, modern scientific medicine requires that, in the 
case of the former at least, the patients should be rigidly protected 
against the bites of mosquitoes, since we know that malaria, like 
yellow fever, can be transmitted in no other way than through the 
bite of that insect, if we except experimental inoculation. In the case 
of relapsing fever, of the manner of transmission of which we know 
absolutely nothing, it would be wise to take the same precaution. 

The epidemics that have ravaged the city of Philadelphia have 
been so graphically described by Rush and later by La Roche that 
one is apt to conclude that the only serious outbreaks this country 
has experienced were those occurring at Philadelphia, New Orleans, 
and one or two other seaports. It is only when we search the litera- 
ture of this disease, that we can appreciate the general devastation 
and terror created by it, and the enormous losses sustained by the 
communities it has visited. In a treatise on yellow fever by Dr. 
Samuel Brown, of Boston, which was published in 1800, he says in 
speaking of the disease: "This is a foe against which neither ramparts 
nor intrenchments afford any security: 'It wasteth at noonday;' and 
every principal town throughout the United States exhibits recent 
and mournful testimonials of its ravages. We will not enter upon a 
particular detail of the distresses which Philadelphia, New York, 
Boston, and other commercial places have experienced; the tale of 
woe would be too afflictive for even the dullest sensibility to bear 
and the feelings of humanity would be agonized to overexcitement." 

In order to show the manner in which yellow fever invades a sea- 
port town, and the mystery attendant upon its appearance and 
spread, I will quote from the report of the committee of medical men 
appointed to investigate the outbreak that occurred at Mobile, Ala., 
in 1819. After giving in detail the condition of the wharves and 



202 YELLOW FEVER. 

docks, the direction of the prevailing winds, and the degree of tem- 
perature and moisture, they state that during the previous winter, 
spring, and summer up to July 1, the city was healthy. "In the 
latter part of July a number of violent cases of bilious fever occurred 
among persons unaccustomed to the climate, and some of a more 
questionable character; several persons employed as workmen in 
filling up one of the new wharves were taken violently ill, and died 
after a short illness of two or three days. About the same time two 
persons usually employed about Dauphin Street Wharf were taken 
in like manner, and died after a short illness. A number of carpenters 
and sailors employed about the wharf, and who were much on board 
the schooner Sally, filled with stagnant water, and about the steam 
sawmill, where there was a pond of like offensive water, were taken 
with violent fevers, and several of them died. The physicians who 
attended these persons died, but it is stated that one of them, Dr. 
Lawton, spoke of them as cases of malignant fever. An engineer 
at work on a steamboat at the same wharf died soon after, his illness 
lasting 5 days. A man who attended him, and a servant boy living 
in the same house, were taken down with a similar fever, and died 
on the third and fourth days. All these persons died with black 
vomit, and were declared by the attending physicians to be cases of 
yellow fever. At about the same time other fatal cases occurred 
among persons whose time was spent about the river and wharves or 
stores in that neighborhood. Within a few days after the prevalence 
of yellow fever was known an exodus took place, and the population 
became reduced from 1,300 in July to 500. Of these, 133, or over 
25 per cent, died." 

The report states that the suburbs of the town, at no greater dis- 
tance than a mile from the river, were as healthy during the prevalence 
of the fever as more distant parts of the country; and the disease was 
not known to be communicated, in any instance, to persons out of the 
town by the removal of and attendance upon the sick. Hence, it was 
concluded that the disease was only communicable in the atmosphere 
in which it originated, and even then some other cause, not under- 
stood, appeared to be necessary, because "a number of persons fre- 
quently in the room with the sick, dying, and dead, in circumstances 
of the greatest exposure, never took the fever. " It is further remarked 
that Natchez and other ports on the Mississippi below suffered heavily, 
and practically every seaport on the Atlantic and Gulf coasts appeared 
to have suffered more or less that summer from yellow fever. It is 
very interesting to note how the disease almost invariably first made 
its appearance in the vicinity of wharves and shipping, in parts of the 
town where surface drainage is usually more or less defective, and 
decaying wood and vegetable refuse are necessarily present. As these 
were the only special conditions found to prevail in these localities, it 
was quite generally conceded that to them the disease owed its origin. 
When vessels with yellow fever on board arrived in port, efforts were 
made to conceal the nature of the disease, and by false entries when 
patients were buried at sea, or by burial at night where death occurred 
in port, many cases are known to have been concealed. Again, a 
vessel with an immune crew, but infected mosquitoes on board, would 
infect persons from shore who visited the ship for various purposes, 
yet, there being no sickness on the vessel, she was relieved of suspicion 
and the disease was assumed to be of local origin. Cases resembling 



YELLOW FEVER. 203 

yellow fever, but without black vomit, were called bilious fever, and 
under this guise, aided by the occasional concealment of an undoubted 
case, the disease frequently escaped detection for weeks and months. 

In the description of the epidemic at Baltimore, also in 1819, as 
observed by various practicing physicians, we find many statements 
that must now be regarded with special interest. For instance, it was 
conceded by all that the first cases appeared at Fell's Point, where the 
principal docks and wharves were located. One observer states that 
the disease never originated more than two or three hundred yards 
from the water, and it was six weeks from the commencement before 
the disease had spread much more than 100 yards from the place of 
origin. The transmission of the contagion was rightfully attributed 
to some unknown agent present in the atmosphere, for in speaking of 
the infection it is said, "upon this ground, then, it may be asserted that 
some matter which was foreign to the natural composition in the air 
of this place floated about with it at this time. Some portion of 
whatever this air contained was therefore of necessity breathed or 
swallowed by the people who came within its limits. And the 
properties of the foreign matter in this air must be decided upon by 
the effects which it has had on those who receive it into their habits." 
We have only to add the mosquito now, and the general truth of the 
above statements becomes manifest. And with the mosquito we 
necessarily include the insect's bite as an additional and at that time 
unknown avenue of entrance for disease. Conceding this, how easily 
one can explain the first appearance and prevalence of the disease in 
the localities where the conditions are favorable for the multiplication 
of mosquitoes, viz, in the low-lying and generally poorly drained 
districts in the vicinity of the wharves and shipping. When we con- 
sider further that the mosquito that transmits yellow fever is a tropic 
and subtropic insect and that, practically speaking, it is not found 
north of Mason and Dixon's line, it then becomes absolutely clear that 
yellow fever in epidemic form can be introduced into that section 
only when the presence of high atmospheric temperature and moisture 
afford conditions favorable for the propagation of this insect. But 
the yellow-fever mosquito is a tropic insect, and yellow fever is a tropic 
disease; it follows, therefore, that, given the proper conditions as to 
temperature and moisture, there must have been introduced at that 
time both the proper insect and cases of the disease. These must 
necessarily have come originally from infected localities within or near 
the Tropics. 

In the days when yellow fever prevailed in our northern seaports 
outbreaks invariably followed the arrival of one or more vessels 
from Habana or some other infected port, but the interval elapsing 
between the entry of the vessel and the recognition of the disease 
was so long and the manner of extension of the disease was so mys- 
terious that it became impossible to trace the connection between the 
one and the other. Let us suppose, for example, in the month of 
July, at a time when yellow fever prevailed and before the days of 
rigid quarantine, a sailing vessel lying at Habana and bound for 
Baltimore. She is tied up at a dock, and numbers of the yellow- 
fever mosquitoes, which are the prevailing house mosquito at Habana, 
fly aboard. They deposit their eggs in open casks, pitchers, or other 
receptacles containing fresh water exposed to the air. The crew are 
immune with one exception, and this man is taken sick three or four 



204 YELLOW FEVER. 

days out from Habana on the journey northward. He has yellow 
fever, but his temperature is only moderately high, and although 
he is deeply jaundiced there is no black vomit. The captain insists 
the case is one of bilious remittent fever and not yellow fever. No 
one could question his statement, because even the best physicians were 
unable at that time to draw the line between yellow fever and malarial 
fever, and it is not always easy to do it to-day. The hypothetic case of 
genuine though unrecognized yellow fever is bitten by a number of mos- 
quitoes during the first three days of his fever, but no one is aware of it, 
or would attach any importance to it if they knew. In two weeks 
the patient is practically well, and in another week or two the vessel 
arrives in port with a clean bill of health. There is no sickness on 
board, she is in fairly good condition, and ties up to the dock in 
Baltimore — say 25 or 30 days after leaving Habana, and with several 
infected mosquitoes on board. 

Perhaps these mosquitoes are disturbed by the unloading of 
the ship or cleaning of the cabins, and they may fly onto another 
ship tied up at the same wharf or travel along the wharf to a watch- 
man's house or some other dwelling in the immediate vicinity. The 
first cases of the outbreak may appear on the other ship tied up at 
the dock, and this latter vessel may have come from Europe and 
be in rather foul condition. The infection in that case would be 
attributed to the foul air generated by the action of a hot atmosphere 
upon the decomposing matter present in her hold. The next case 
may appear in some one sleeping or employed on the dock or on a 
neighboring vessel. In the month of August conditions would be 
favorable for the propagation of mosquitoes, and in addition to those 
hatched out on the trip from Habana another brood will soon have 
appeared on shore. The mosquito may also have been introduced 
by other vessels earlier in the season, and the conditions will then 
be suitable for a further extension. The continuance of the out- 
break necessarily depends on the coming together of the imported 
mosquitoes and cases of yellow fever in the first three days of the 
disease; consequently in numerous instances only one or two cases 
occur, and none follows unless fresh cases are introduced by other 
vessels from infected ports. The frequency of the occurrence of 
cases of bilious remittent fever in American ports during the last 
century shows that during the early part at least yellow fever was 
being constantly imported, though it only occasionally assumed 
epidemic proportions. Let us suppose that the vessel leaving Habana 
sailed for New Orleans, Mobile, or Galveston, instead of Baltimore. 
Here the case will be different, because in these places the conditions 
are favorable for the propagation of the yellow-fever mosquito 
throughout the greater part of the year, and the introduction of a 
single case might prove sufficient to light up an epidemic, because the 
proper mosquito is at nearly all times present in the houses in abun- 
dance. Frequent severe outbreaks have occurred at New Orleans 
until a large part of the population had become immune, and those 
who were nonimmunes and could afford it habitually left the city 
during the warm season. Among the few who remained and chanced 
to be bitten by the proner infected mosquitoes, cases would occur 
from time to time as bilious fever, often suspected to be yellow 
fever, but for reasons of policy they were not so reported. Finally, 
after a few years had passed, confidence would be restored, and a 



YELLOW FEVER. 205 

larger proportion of nonimmunes would supply the material for a 
fresh outbreak, which was certain to appear sooner or later. Then 
came a sudden exodus, with the wrecking of commercial interests, 
neglect of the sick, and the untold suffering known only to those who 
have passed through a severe epidemic. Here let me remark with 
emphasis that for the production of an outbreak of yellow fever 
three factors are necessary: (1) Preexisting cases of the disease, 
(2) mosquitoes of the genus Stegomyia, and (3) nonimmunes or per- 
sons who are susceptible to the disease. I would impress upon you 
the fact that the absence of any one of these factors will render it 
absolutely impossible for an outbreak to occur. An epidemic of 
yellow fever is impossible in the absence of preexisting cases, for the 
disease can not be generated by any amount of filth, heat, moisture, 
or decomposition without the intervention of the three factors 
named. Excluding experimental inoculation, the occurrence of 
cases of }^ellow fever is not possible under any conditions without the 
presence of the proper mosquito to transmit the infection from the 
sick to the well. And, finally, given any possible local conditions, 
any number of cases of yellow fever and any number of infected 
mosquitoes, in the absence of susceptible persons, cases of the disease 
must disappear. 

But I am going faster than I ought. Here in Galveston you 
are in the epidemic zone of the disease; you have had your epi- 
demics, and you have reason to guard against them in the future. 
Your city was described 30 years ago as being built upon an island 
composed of shingle, and this shingle so saturated with water that 
the latter could be found at a depth of a few inches. The mean 
temperature is about 74°, and the rainfalls are usually heavy in 
April, May, and June. Owing to the saturation of the deeper layers 
of the soil, the rain water lay upon the surface in pools until it disap- 
peared by evaporation in the dryer months of the late summer and 
autumn. The surface pools of fresh water were ideal breeding places 
for mosquitoes, as also were the receptacles for rain water, which the 
early inhabitants collected and used after the custom at New Orleans. 
Yellow fever paid its first notable visit here in 1839, only a few years 
after the establishment of the first settlement. The population was 
about 1,000, and the people were located mostly along the Strand, 
in close proximity to the wharves and vessels. The first case reported 
occurred late in September on a steamer recently arrived from New 
Orleans. At about the same time another case occurred on a vessel 
anchored only a few yards from her. Both cases were fatal. As 
others were reported on land at the same time, it is more than likely 
that these were not the first cases, but as they were the first in which 
black vomit appeared they were probably the first in which a diag- 
nosis of yellow fever could no longer be withheld. In this epidemic, 
which lasted less than two months, we are told that there were 250 
deaths, which means the occurrence of at least twice as many cases 
among the population of 1,000 persons. It is further stated that the 
epidemic died out because " every unacclimated person had either 
fled from the town or suffered an attack. This was proved by the 
fact that when the refugees began to return the disease broke out 
again among the newly arrived, and there were a number of deaths." 
How beautifully this all fits in with the mosquito theory, now that 
we know that the bite of the mosquito can convey the disease as long 



206 YELLOW FEVER. 

as two months after it has bitten a yellow fever patient. I have 
good reason to be a firm believer in the theory of the transmission of 
the disease by the mosquito, for I have seen 16 cases of experimental 
yellow fever produced by the application of infected insects, and it 
was my good fortune to be the first case among them. Among other 
experiments it was my; privilege to apply two mosquitoes of the 
proper genus (Stegomyia) to a patient suffering with yellow fever, 
and 57 days later I applied the same mosquitoes to a soldier volun- 
teer, who had been kept in strict quarantine for 78 days. In four days 
he was taken ill with a typic attack of yellow fever, from which he 
made a good recovery. 

Keturning to the subject of Galveston, a few cases are said to 
have appeared in 1842, but in 1844 a violent outbreak raged for 
about six weeks, and then ceased suddenly from the absence of sus- 
ceptible persons. Here it was again noticed, however, that non- 
immunes who visited the town but once for the purpose of shopping, 
etc., occasionally returned home to be taken ill with yellow fever a 
few days later. This continued until the appearance of a white frost, 
which we know benumbs the mosquito and forces it to go into hiber- 
nation. This, therefore, affords a rational explanation of the effect 
of the first sharp frost, which has so long been welcomed as the 
savior of districts afflicted with yellow fever. During the epidemic 
just mentioned nearly 400 deaths occurred in a population of about 
4,000. 

Three years later, in 1847, an epidemic was declared to be present 
in the month of October and there were about 200 deaths in a popu- 
lation of 4,800. In 1853, after an immunity of six years, the deaths 
from yellow fever were 535; in 1854, 404; in 1858, 873; and in 1859, 
183 in a population of about 10,000. 

In September, 1864, the disease was again epidemic, the deaths 
being 259 and the population 5,500. Three years of exemption fol- 
lowed, and in 1867 a severe epidemic is estimated to have produced 
8,000 cases and 1,150 deaths in Galveston in a population of 15,000. 
From Galveston it was carried to a number of smaller towns, among 
which Alley town on the Colorado River was afflicted with 200 deaths 
and about 800 cases in a population of 1,500. 

During the same season Indianola is said to have received the 
infection from Vera Cruz, and we are told that "in less than a week 
the whole business part of the town was struck down as by lightning, 
there being no less than 125 to 150 cases taken during that time out 
of a population of less than 1,000." The extension of the disease 
was checked by a rapid depopulation of the town. The number 
of deaths among the citizens was about 75. From Indianola the 
disease is said to have been carried to various points throughout 
the State and even beyond. In 1870 and 1873 a few cases occurred, 
but the disease did not assume epidemic form. There is reason to 
believe, also, from the report of Dr. H. A. West, of this city (Galveston), 
that there were a few mild cases in 1897. I can find no record of 
any outbreak in Galveston since that time, although two cases were 
introduced on December 31 last, but as you well know there were 
in the State of Texas in 1903 over 1,200 cases of yellow fever, with 
nearly 140 deaths. Over 1,000 cases and 107 deaths are recorded 
for Laredo alone, and if it were not for the energetic measures insti- 
tuted against the mosquito there would undoubtedly have been 



YELLOW FEVER. 207 

another fearful epidemic to record for the United States similar 
to that of 1878, during which, according to the Board of Experts 
appointed by Congress, more than 100,000 persons were stricken 
in their homes, and 20,000 lives were sacrificed in a single season. 
In Memphis alone, according to Keating, there were in 1878, 17,600 
cases of yellow fever, with 5,150 deaths, a mortality rate of about 
1 in 4 of the reduced population. Scenes were enacted there similar 
to those described by Rush in his account of the epidemic at Phila- 
delphia almost a century before, when the streets became deserted, 
bodies remained unburied, friends no longer shook hands upon 
meeting, husbands deserted their wives, wives their husbands, and 
parents their children. So, in Memphis, we are told of a prominent 
man who fled the city and refused to return when his wife and chil- 
dren were stricken and who still remained 50 miles away when notified 
of their death. These deplorable incidents, however, were more 
than offset by numberless instances of heroic devotion on the part 
of Sisters of Charity, nurses, and physicians who died at their posts 
of duty. As one illustration I might cite from the little book on 
yellow fever published in 1898 by Dr. W. L. Coleman, of Houston. 
Dr. Coleman was present during the Memphis epidemic and took 
down the names of 45 volunteer physicians immediately after their 
arrival. Most of them came from the Northwest, and one did not 
remain. The others all contracted yellow fever and 30 of them were 
dead within a month. 

At that time no one could say how the disease was contracted; 
some held that it was of local origin and contagious, others that it- 
was not contagious; many believed it was imported, that it was 
infectious but not contagious, and was carried in some mysterious 
way by the atmosphere. We are told by Keating that "Dr. Dowell, 
of Galveston, says that in 19 cases out of 20 it will be found to have 
been introduced or imported, " which was wonderfully near to the 
truth as we know it to-day. 

It may surprise you to learn that yellow fever experimental 
inoculations began in the United States in Philadelphia, during the 
yellow-fever epidemics in the years 1802 and 1803. It is a fact that 
in those years Stubbins Firth, a medical student of the University 
of Pennsylvania, deliberately experimented upon himself by placing 
fresh black vomit and blood serum obtained from yellow-fever 
patients into wounds made in his arms and legs. Failing in this, 
he inhaled the fumes from black vomit, which he heated over a sand 
bath in a small room, and then, making the residue into pills, he 
swallowed them. He administered black vomit to animals, injected 
it into their circulation, and deposited it in their tissues. As the 
results of these and other experiments were negative, he concluded 
that yellow fever was neither infectious nor contagious, and reported 
his work and conclusions in a graduation thesis in 1804. 

But little more was done or could be done until the advent of the 
new science of bateriology encouraged the belief that this mysterious 
malady might be caused by a bacterium. The first to claim the 
discovery of the specific cause of yellow fever was Dr. Domingo Freire, 
of Brazil, who went further than this, and claimed also that he had 
conferred protection against the disease by inoculations with specially 
treated cultures. He was followed by Dr. Carmone y Valle, of Mexico ; 
Dr. Babes, of Brazil; Dr. Gibier, of Paris; and Dr. Finlay, of Habana, 



208 YELLOW FEVEE. 

each of whom believed that he had found the cause of yellow fever 
in a different organism. It remained for Dr. Sternberg to show that 
these investigators were all mistaken, and that the bacteria found 
by them were not in any way related to the disease. Dr. Sternberg, 
himself, subsequently exhausted the field so far as the search for 
bacteria was concerned; he also made extremely careful and thor- 
ough examinations of the blood and tissues obtained from patients 
with yellow fever. He announced finally that his search had proved 
unsuccessful, and his work stands as the best that has ever been done 
in the study of the bacteriology of the disease. 

In 1897 the sensational announcement was made that Dr. Guiseppe 
Sanarelli, an Italian bacteriologist, working upon the island of Flores, 
in Montevideo, had discovered the cause of yellow fever in a bacillus 
that he had found in about 50 per cent of the patients examined by 
him. He reported also that the injection of pure cultures of this 
bacillus into the circulation of dogs brought about an infection 
similar to yellow fever in the human being, with the vomiting and 
other symptoms of that disease, and a similar condition of the organs 
after death. This announcement naturally interested Dr. Sternberg, 
who at this time had become Surgeon General of the Army, and he 
immediately turned to an organism that he had obtained from about 
50 per cent of the patients examined by him, that he had found to be 
exceedingly virulent for the small laboratory animals, and which he 
had called Bacillus X, because he had been unable positively to iden- 
tify it. He obtained a culture that had been preserved by one of his 
former assistants, and directed Dr. Reed and myself to undertake 
certain experiments with it. As Dr. Sternberg had never injected it 
into dogs, one of the first steps in our work was a duplication of some 
of Dr. Sanarelli's experiments, viz, to inject it into the circulation 
of dogs. We obtained the same effects as Sanarelli had recorded for 
his yellow-fever bacillus, and this seemed to indicate that the organ- 
isms must be identical. Dr. Sternberg then procured a culture of 
Sanarelli's bacillus from Prof. Roux, of Paris, and handed it to us for 
comparative study. It is amusing now to think of the fearful respect 
with which we handled the culture from Dr. Sanarelli's laboratory, 
because we were fully prepared to accept it as the cause of yellow fever 
from what we knew of Dr. Sanarelli's reputation as a bacteriologist. 
After several months it became apparent that this supposed yellow- 
fever bacillus of Sanarelli was nothing more nor less than the common 
hog-cholera bacillus, an organism that was much better known in 
America than abroad. Sanarelli was evidently at that time not 
familiar with the bacillus of hog cholera, for he pronounced the germ 
obtained by him "the strangest of all microbes that are known." A 
bitter controversy arose upon the publication of our reports of the work 
in which we had found that Dr. Sanarelli's bacillus when fed to young 
hogs would produce the symptoms and lesions of hog cholera. Indeed, 
Sanarelli still contends in his own country that he found the bacillus 
of yellow fever, a contention that finds no support to-day among repu- 
table bacteriologists in this country or in Europe. 

It is a remarkable fact that upon his own demonstrations alone, Dr. 
Sanarelli was awarded large pecuniary prizes and honors as the dis- 
coverer of the causative agent of yellow fever. Unfortunately, 
Archinard and Woodson, and a commission from the Marine-Hospital 
Service, working in the United States, reported that their results con- 



YELLOW FEVER. 209 

firmed the claims of Dr. Sanarelli. In 1897 and 1898, the latter com- 
mission, consisting of Drs. Wasdin and Geddings, continued their 
investigations in Habana, and in 1899 an elaborate report was issued, 
in which it was claimed that dogs, rabbits, mice, and other animals 
could be given yellow fever by infecting them with Sanarelli's bacil- 
lus, that infection took place through the lungs, and that a diagnosis 
of yellow fever could be made by isolating the bacillus from the blood 
of the patient. This made* matters rather interesting for us, but did 
not shake our confidence in our results. Bacillus X (Sternberg) was 
found to belong to the group of colon bacilli. 

Finally, in 1900, during the American occupation of Cuba, yellow 
fever became epidemic in Habana. To take advantage of the oppor- 
tunity thus offered, Gen. Sternberg designated a board to meet at 
Habana, for the purpose of continuing the study of that disease. The 
members of that board were Drs. Walter Reed, James Carroll, Aris- 
tides Agramonte (a Cuban immune), and Jesse W. Lazear. Drs. 
Lazear and Agramonte were already at Habana, and we joined them 
there in June. Our first aim was to confirm or disprove the claim for 
Sanarelli's bacillus, which he had called B. icteroides, and after a most 
painstaking and careful investigation of the blood obtained during 
life from 18 undoubted cases of yellow fever, and of the blood and 
tissues of 11 fatal cases after death, we were compelled to report that 
we had failed to find Bacillus icteroides in a single instance. 

Having thus disposed of B. icteroides, two lines of work now pre- 
sented, one an investigation of the mosquito theory, so long advo- 
cated by Dr. Carlos Finlay, of Habana, the other a study of the micro- 
organisms present in the intestinal canal of yellow fever patients. The 
former was chosen, because of the numerous points of resemblance 
between yellow fever and malaria, which was known to be conveyed 
by the mosquito. Both diseases are airborne; both are contracted 
mostly at night; both jump from house to house in a mysterious way; 
both are noncontagious; both prevail in the season when mosquitoes 
are numerous, and infections cease to occur upon the appearance of 
a sharp frost; the interval of time elapsing between the occurrence 
of the first case and secondary ones in primarily infected dwellings 
suggested the necessity for an intermediate host in the conveyance of 
yellow fever; it was noted that in a large military command at Colum- 
bia Barracks, near Habana, the only persons who contracted yellowf ever 
were those who left the camp after sundown, and these, after recov- 
ery, although they mingled freely with their comrades, never infected 
them. This latter observation seemed to show that the cause of the 
disease was not present on the body, in the clothing, or the dejecta. 
A consideration of all these points led us to decide that the next step 
should be to test the mosquito theory. In the early consideration 
of this line of work the members of the board paid a visit to Dr. Finlay, 
who received them most courteously, showed them the common house 
mosquito that he believed to be responsible for the disease, narrated 
the work that he had done, and kindly supplied them with some dried 
mosquito eggs for the purpose of hatching them out for study. The 
moral responsibility was next considered, and in a later conference it 
was agreed that the members of the board would themselves be bitten, 
and subject themselves to the same risk that necessity compelled 
them to impose on others. 

79965°— S. Doc. 822, 61-3 14 



210 YELLOW FEVEK. 

Dr. Lazear was given charge of the mosquito work, because he 
already had had experience with other mosquitoes. I was to con- 
tinue my work with the cultures, and Dr. Keed returned to the United 
States. Dr. Lazear made a number of unsuccessful attempts with 
mosquitoes, applied one or several days after biting a patient as Dr. 
Finlay had done, and he himself was bitten by a mosquito that he 
had applied to a mild case of yellow fever 10 days before. I reminded 
Dr. Lazear that I was ready, and he at last applied to my arm an 
insect that had bitten a patient with a severe attack 12 days pre- 
viously. Four days later I had fever, and on the day following I was 
carried to the isolation camp as a patient with yellow fever. On the 
day that my fever appeared, Dr. Lazear applied the same mosquito, 
with three others, to a soldier, X. Y., who was taken sick on the fifth 
day following, and passed through a comparatively mild attack. 
Scarcely more than a week later, Dr. Lazear was applying mosquitoes, 
as usual, late in the afternoon, to patients in the yellow fever hospital, 
known as Las Animas, and while thus engaged a mosquito alighted 
upon his hand. He allowed it to take its fill, and concluded it was 
one of the common culex mosquitoes which were present in the hos- 
pital in large numbers. So little importance did he attach to the 
incident that he made no note of it, and related the circumstance to 
me when he was first taken sick, fire days afterward. A week from 
that date he died, having been delirious and affected with black vomit 
for several days. Thus ended the first set of experiments, with the 
death of our esteemed and unfortunate colleague. 

Two months later a new series of experiments was instituted for 
the purpose of confirming the results already obtained, to see, also, 
whether the disease could be contracted from exposure to soiled or 
contaminated articles of bedding, clothing, etc., and to determine 
whether or not the infectious agent was present in the blood. 

For the first-mentioned experiments an isolation camp, called 
after our deceased comrade "Camp Lazear," was established in a 
secluded spot about a mile from Columbia Barracks and apart from 
any habitation. In this camp there were placed three immunes and 
nine nonimmunes, including one immune and one nonimmune phy- 
sician. A strict quarantine was maintained and only the immunes 
were permitted to leave the camp. If a nonimmune left, he was not- 
permitted to return. As newly arrived nonimmune Spanish immi- 
grants could be obtained from the immigrant station at Habana they 
were brought out and added to the command in quarantine. The 
camp consisted of seven large hospital tents, separated by a wide 
interval and pitched in the arc of a circle. The nonimmunes dis- 
tributed through the tents were required to sleep beneath mosquito 
bars, and the rule was rigidly enforced. The plan was to nick out 
men here and there in the line of tents, bring them down with infected 
mosquitoes, and in that way establish the fact that cases could be 
produced at will by the application of infected mosquitoes. It was 
further desired to show that an infected house was simply one that 
contained active infected mosquitoes, and that nothing more was 
necessary for the production of an epidemic in a susceptible commu- 
nity. A new, tightly ceiled frame building was constructed, 20 feet 
by 14 feet, provided with two small windows, tightly closed with 
fine-mesh wire screens; also with two vestibules protected by an 
outer door, and an outer and an inner tightly fitting screen door, so as 



YELLOW FEVER. 211 

to guard against the ingress of mosquitoes from without or their egress 
from within. Upon entering the vestibule the screen door through 
which one passed was closed, and the other was not opened until it 
was made certain that no mosquitoes were passing in or out. The 
lumber used in the building was tongued and grooved; the walls were 
battened on the outside and lined with white cotton cloth within. 
The walls and floor were double, and all crevices were stopped; the 
ceiling was covered with cloth and made so low that mosquitoes resting 
upon it could be captured with ease. Across the middle of this room 
there was built a wire-screen partition extending from floor to ceiling 
and dividing it into two compartments, each with a separate entrance. 
Beds were placed in each of these rooms, and one of them was 
occupied by two nonimmunes for 18 consecutive nights. The bed- 
ding and other articles admitted to the room were all disinfected. 
On December 21, 1900, the date of the first occupation, 15 contam- 
inated mosquitoes were turned loose in the unoccupied compartment, 
and then a nonimmune entered and lay upon one of the beds, with his 
chest and limbs exposed for 30 minutes. During this time he was 
bitten by several insects and others bit him. again later in the day, 
when he lay there for 20 minutes. This procedure was repeated 
again on the following day, the last of exposure. On December 25, 
four days after his first exposure, this man who had remained in 
strict quarantine, was taken ill with a severe attack of yellow fever, 
from which he recovered. The other two men, who slept in the 
same room but in another compartment, separated from the mos- 
quitoes only by the screen partition, remained in their usual health. 
Another building had been constructed similar to the above, but 
provided with only a single vestibuled entrance. It was equally 
protected against the entrance of mosquitoes and had two small 
screen-protected windows provided with shutters, so as to exclude 
sunlight as well as mosquitoes. It contained a coal-oil stove, by 
means of which the temperature was kept above 90° during the day, 
and the atmosphere was provided with moisture. Into this room, 
which was warm, dark, and moist, like the hold of a ship in the Tropics, 
several boxes containing sheets, blankets, pillow slips, and garments 
direct from the yellow-fever hospital were placed. These had been 
soiled intentionally with black vomit and other repulsive material 
from cases of yellow fever. This room was then entered each evening 
at sundown by two nonimmune Americans, one of them a physician, 
who unpacked the boxes, handled and shook the articles, then hung 
them up on nails in the walls, and retired for the night. Upon rising 
in the morning they removed the articles from the walls, handled 
them freely, and repacked them in the boxes, where they remained 
until evening. This procedure of unpacking and repacking, handling, 
and sleeping in the presence of the soiled materials was kept up for 
20 consecutive nights, and in the meantime fresh supplies were added 
as fast as they could be obtained. On one or two occasions the 
stench drove the occupants out, but they returned again and slept 
there. They spent the daytime in a tent nearby, but were strictly 
quarantined. The pulse rate and temperature of all nonimmunes in 
the camp were recorded three times daily, and showed that the health 
of these men was not affected in the slightest degree; on the contrary, 
thev gained in weight. 



212 YELLOW FEVER. 

These were succeeded by two other nonimmunes after the addition 
of more soiled garments, etc., and they in turn were followed by 
another two for the same period. Some of these men slepi, between 
the sheets and in the garments used and soiled by yellow-fever 
patients at the time of their death, and they even slept with their 
faces upon towels soiled with blood that had been shown by 
inoculation to be capable of infecting with yellow fever. In no 
single instance did any disturbance of health follow these exposures; 
the conclusion was therefore arrived at that yellow fever can not 
be contracted through exposure to fomites. If one stops to reflect 
that the mosquito is not able to infect until 12 days or more after 
contamination, one is forced to the conclusion that the yellow-fever 
parasite, which has never been seen, must, in all probability, pass 
through a distinct cycle of development in the mosquito before the 
insect becomes dangerous. As Dr. Howard has told you, a corre- 
sponding but slightly shorter interval is seen with the mosquito that 
transmits malaria. The developmental phases of the malarial 
parasite in the mosquito are well known and have been demonstrated. 
Judging by analogy, therefore, it seems justifiable to assume that 
the parasite of yellow fever appears also to belong to that group of 
obligate parasites whose whole existence is passed within the bodies 
of two living hosts, one of which, man, is a vertebrate, and the other, 
the mosquito, an invertebrate. This affords an explanation of the 
uselessness of disinfection against yellow fever as well as malaria, 
and it also explains the instances occasionally noted in the literature, 
where a prompt suppression of the disease followed the use of fumiga- 
tion as well as disinfection. 

Returning to the subject of the experiments at Camp Lazear, the 
susceptibility of the men exposed to the fomites or soiled articles, 
was shown by the fact that four of them were subsequently infected 
by means of mosquitoes and blood injections. Four nonimmunes in 
all were infected by the subcutaneous injection of small quantities 
of blood drawn in the first and second days of the disease. This 
established another point of analogy between yellow fever and mala- 
ria, and demonstrated the presence of the infectious agent in the 
blood, notwithstanding that we had failed to discover anything upon 
careful microscopic examination of the blood from many patients, 
including those in whom the blood, drawn at the same time, produced 
yellow fever in persons into whom it was injected. 

Nine additional cases were produced in Camp Lazear by the appli- 
cation of infected mosquitoes, making in all 10 cases of yellow fever 
brought about at will. All were taken sick within the usual period 
of incubation, never more than six days. They were selected here 
and there in the different tents, and no other cases occurred than 
those purposely inoculated. As soon as a case appeared the patient 
was immediately removed to the yellow fever isolation camp, a mile 
distant, to avoid the possibility of any stray mosquitoes becoming 
infected from him. In no instance was the mosquito found to be 
capable of infecting in a shorter period than 12 days after biting the 
patient, and one patient was infected with two mosquitoes kept as 
long as 57 days. 

This work was concluded by the end of February, 1901, when 
confirmatory experiments were taken up by Dr. John Guiteras, of 
Habana. His first patient was infected in February with a mosquito 



YELLOW FEVER. 213 

obtained from the Army commission, and his subsequent inoculations 
were unsuccessful until August, when he succeeded in infecting seven 
persons with mosquitoes. Of these cases, three, unfortunately, 

£ roved fatal. Among the latter was a young American nurse, Miss 
[aas, of Baltimore, who voluntarily submitted herself to the experi- 
ment. 

In August, 1901, I returned to Habana, and obtaining some of 
Dr. Guiteras's mosquitoes, infected two Spanish nonimmunes. 
Drawing blood from one of them and separating the serum, I passed 
the latter through a filter, which was shown to be capable of holding 
back the ordinary bacteria. Injection of the filtered serum into two 
Americans infected them with yellow fever. In this way it was 
shown that bodies smaller than ordinary bacteria were capable of 
producing yellow fever upon injection, and our failure to discover 
anything upon microscopic examination of the blood of yellow fever 
patients was thus satisfactorily explained. It was further shown, as 
a point of great scientific interest, that blood that was known to be 
capable of producing the disease was found to be absolutely harmless 
after it had been heated to 131° F. for 10 minutes. At this time I 
produced six additional yellow fever cases, all of whom recovered. 

Such were the results obtained by the Army board, and they can 
be summarized as follows: 

1. Bacillus icteroides of Sanarelli was shown to be practically 
identical with the bacillus of hog cholera, from which it differs only 
in the source from which it is obtained. 

2. Yellow fever is transmitted by a mosquito of the genus Stego- 
myia, and all attempts to bring about the infection through contact 
with bedding, clothing, and dejecta of yellow fever patients have 
resulted in failure. Hence it follows that disinfection against yellow 
fever is valueless. 

3. Yellow fever can be produced experimentally, by the injection 
of blood drawn in the first and second days of the disease, but this has 
no direct bearing upon the transmission or prevention of the disease 
in its epidemic form. 

4. The specific germ of yellow fever is sufficiently minute to pass 
through the pores of a bacteria-proof filter, and it is destroyed by a 
temperature of 131° F. 

Confirmation of the mosquito inoculations has been furnished by 
Dr. Guiteras, in Habana; Drs. Ribas and Lutz, as well as the French 
commission, in Brazil, and by a commission of the United States 
Public Health and Marine-Hospital Service, at Veracruz. It is espe- 
cially gratifying that a French commission from the Pasteur Institute, 
working recently in Brazil, has confirmed practically all the results of 
the American Army commission. 

The following, therefore, may be safely assumed: 

1 . Disinfection in the prophylaxis against yellow fever is effective 
only when it takes the form of fumigation and destroys mosquitoes. 

2. Yellow-fever patients can be the source from which other cases 
spring only when they have been bitten by the proper mosquitoes; 
consequently, in the yellow-fever zone all acute febrile cases not 
diagnosed should be handled as though they were yellow fever, and 
should be kept rigidly behind safe mosquito screens and netting. 
So far as has been shown the yellow-fever patient is dangerous when 
bitten by mosquitoes during the first three or four days of the fever 



214 YELLOW FEVER. 

only, but since relapses may occur, every precaution should be 
maintained as long as the temperature remains elevated. 

3. The hospitals intended for the treatment of suspected cases of 
yellow fever should be located upon ground that is high, well drained, 
away from creeks, pools, or standing water of any kind, free from 
mosquitos, and not surrounded by grass or shrubbery. All entrances 
and exits to such hospitals should be provided with close-meshed 
wire screen spring doors, and similar screens should be fixed immov- 
ably over every window and other opening communicating with the 
exterior. Standing water should not be permitted in barrels or 
vessels of any kind, and broken crockery, tin cans, or other possible 
retainers of rain water should be systematically searched for within 
a radius of several hundred yards, and removed. 

4. In general sanitation, all surface pools should be promptly 
drained and filled in with gravel, or covered with petroleum. Petro- 
leum should be applied s^ystematically to standing water in all ditches, 
pools, rain-water gutters, etc., that can not be filled up or emptied. 
The margins of ponds should be deepened, to enable the fish to reach 
mosquito larvae. 

5. Water should not be permitted to stand uncovered in houses; 
and rain water in cisterns or barrels, when not used for drinking 
purposes, should be treated with petroleum; if the water is used for 
drinking, all openings, vents, etc., should be closed with wire screens 
or tightly fitting covers. Periodic examinations should then be 
made for wigglers (larvae) or mosquitoes, because the female mosquito 
may pass through a very minute opening when seeking water on 
which to deposit her eggs. By means of these and other similar 
measures, the number of mosquitoes may be greatly reduced, and the 
chances for the conveyance of the infection, should it happen to be 
present, will be thereby greatly diminished. 

Stegomyia fas data, the yellow-fever mosquito, is a house-dwelling 
and house-breeding insect; particular attention should therefore be 
paid to the smallest as well as the larger collections of standing water 
within and about habitations. 

6. After the removal of a patient, his room and the adjoining ones 
should be at once tightly closed by pasting paper oyer all cracks and 
openings, and then fumigated with insect powder, tobacco, or sulphur, 
to destroy mosquitoes. When the room is opened after a few hours 
these should be swept up and burned. 

7. Experience at Habana has shown that patients suffering from 
yellow fever upon their arrival at a port can be carried through a 
thickly populated city to a properly screened hospital, and there 
treated without the slightest danger to the community, so long as 
they are rigidly protected against mosquitoes. Money spent for the 
purpose of disinfection against yellow fever is wasted, for yellow 
fever in epidemic form can only be contracted through the bites of 
mosquitoes of a single genus. 

8. The noncontagiousness of yellow fever was clearly shown in 
certain localities years ago before the use of disinfectants, in places 
where the yellow-fever mosquito did not exist. The belief m the 
supposed contagiousness of this disease arose from its transmission 
through the atmosphere by the mosquito at a time when this insect 
was not suspected or known to be concerned in the transmission of 
any disease. 



. YELLOW FEVER. 215 

9. When a house is infected with yellow fever, it simply contains 
infected mosquitoes; in the absence of this insect, no amount of 
filth, heat, or moisture is capable of generating the disease. 

10. Vessels from infected localities should be compelled, upon 
entering port, to anchor at least a fourth of a mile from shore; they 
should never be permitted to tie up to a wharf or dock in the city, 
except in northern latitudes during the cold season of the year. In 
this way, the chances for contaminated mosquitoes reaching the city 
can be reduced to a minimum. 

11. As the yellow-fever mosquito does not bite, as a rule, between 
the hours of 9 a. m. and 3 p. m., it is practically safe for nonimmunes 
to visit infected localities between these hours for the transaction of 
business. Before 9 a. m. and after 3 p. m. they will run a greater 
or lesser risk of being infected. 

12. It is now certain that before the lapse of many years, the dis- 
ease, yellow fever, will have become extinct. The length of time 
necessary for its complete eradication will depend upon the readiness 
of our southern neighbors to accept the mosquito theory in toto, 
and institute in their infected seaports vigorous and energetic meas- 
ures based upon it. 

13. Another epidemic of yellow fever should never be seen in the 
United States. An example has been shown in Cuba, and the meas- 
ures necessary to prevent the extension of the disease are so simple, 
so plain and practicable for persons in authority, that the existence 
of an epidemic of yellow fever in our country should alone be regarded 
as prima facie evidence of the culpability of some responsible person. 

In conclusion, I can not refrain from asking you to pay no atten- 
tion to the sensational letters, already referred to, as recently pub- 
lished from a well-known American physician on the island of Cuba, 
This gentleman was at one time regarded as an authority upon yellow 
fever, of which he has seen a great deal, but he is now five years 
behind the time. His insinuation that cases of yellow fever are still 
frequent in Cuba, and that they are called typhoid fever, is a scan- 
dalous misrepresentation of the actual truth, and an unjustifiable 
reflection upon the intelligence and zeal of Cuban physicians, like 
Drs. Finlay, Guiteras, Agramonte, Albertini. and others, who realize 
fully the responsibility that rests upon them, who have suppressed 
yellow fever on the island for three years, and who are fully compe- 
tent to deal with the situation there, now and in the future. 



Chapter 4. 

LESSONS TO BE LEARNED FROM THE PRESENT OUTBREAK OF 
YELLOW FEVER IN LOUISIANA. 1 

By James Carroll, M. D., Assistant Surgeon, United States Army, Washington, D. C. 

The present seems to be a suitable occasion to invite attention to 
several points in connection with the epidemic occurrence of yellow 
fever in the United States at the present as well as at other times. 
In the discussion of the symposium on yellow fever at the meeting of 
the American Public Health Association in Washington in 1903, I 
called attention 2 to the necessity during the epidemic season for 
requiring physicians, in cities where yellow fever is prevailing or 
likely to prevail, to report promptly to the authorities all cases of 
fever of any kind coming to their notice. This is necessary in order 
that there may be no delay in the institution of proper measures to 
protect the community against extension of the disease if it be yellow 
fever, for this extension will almost surely take place in the more 
southern latitudes if the patients are not protected from mosquitoes 
at the outset. If all cases of undetermined fever were promptly 
reported and at once protected from mosquitoes 3 it would hardly 
be possible for the disease to spread if it were yellow fever; on the 
other hand, where the physician waits for the appearance of black 
vomit, the golden opportunity passes by, for it has been shown that 
in practically all cases the disease can not be communicated after 
the fourth day of the fever. For this reason the diagnosis should be 
anticipated, and all febrile patients should be immediately protected 
from mosquitoes until it is shown by actual demonstration that they 
are not suffering from this disease. Epidemics do not follow every 
introduction of yellow fever; mosquitoes becoming infected may 
die before they bite a nonimmune, or the patients may happen to be 
treated in a locality free from Stegomyia. A group of cases of yellow 
fever occurring without black vomit usually receives the designation 
bilious remittent fever, a diagnosis that should be erased from our 
text books. Bilious remittent fever, acute in type and of short dura- 
tion, appearing in the United States, is yellow fever, and it should 
be so regarded. Bilious remittent fever was formerly regarded as a 
type of malarial remittent, but that was before the use of the micro- 
scope was found to be necessary for a positive diagnosis of malarial 
infection. We know now that malarial fever is not a disease of cities, 
but of outlying districts, while the bilious remittent fever, so called, 
has been recorded in the cities, in epidemic form, and in such intimate 
association with yellow fever that by some the diseases were declared 
identical, and by others the latter was said to be only a modification 

1 Read at the thirty-first annual meeting of the American Public Health Association at Boston, Sept. 
25-29, 1905. 

2 Report of the Proceedings of the American Public Health Association, vol. xxix, p. 291. 

3 Since this paper was read, I have been informed by Dr. E. Liceaga, president of the Superior Board 
of Health of Mexico, that the line of procedure indicated is now being followed in his country. 

216 



YELLOW FEVER. 217 

of the former. Most interesting and important in this connection is 
the statement cited by La Roche, 1 in his chapter on bilious remittent 
fever, that '' the morbid appearances revealed on dissection are the 
same in remittent as in yellow fevers. 1 ' This statement, however, 
was not whoUy accepted by him, for he calls attention to the bronzed 
appearance of the liver in certain remittents, a condition that we 
know results only from malarial pigmentation. Xow that we can so 
easily differentiate malarial remittent and typhoid from yellow fever, 
the diagnosis is much less difficult, except where yellow fever occurs 
as a complicating infection. 

Our confreres in Havana have demonstrated to us that it is pos- 
sible to prevent the epidemic occurrence of yellow fever, while occa- 
sionally admitting cases of the disease into the heart of a city in which 
the climatic and other conditions are known to be most favorable for 
its extension in epidemic form, and in which there are more suscep- 
tible persons now than ever before. The method suggested here is in 
many respects similar to, and is based on, the one adopted during the 
American occupation of Havana. 

Since then it has been sufficiently demonstrated, in 1903 and again 
in 1905, that under the lax system heretofore and now in vogue, 
yellow fever can easily secure a firm foothold in certain of the south- 
ern states and escape recognition until it has passed almost com- 
pletely beyond control. On both occasions cited, the outbreak was 
suppressed or limited only by the intervention of the General Govern- 
ment, which, through the energetic action of the United States 
Public Health and Marine-Hospital Service, finally succeeded in 
checking two epidemics that threatened to become little less than 
national calamities. Great credit is due to those officials for the 
success that was attained in spite of the extreme delicacy of the 
situation and the passive opposition encountered from many quarters. 

Our experiences in Cuba have shown that for the exclusion and 
suppression of yellow fever absolute hygienic control is necessary 
not only of the people at large, but of the patients as well, and espe- 
cially of the practicing physicians. The aim of modern medicine is 
the prevention of disease rather than its cure, and the safety and 
welfare of the thousands of persons exposed demand that the proper 
measures be instituted and rigidly enforced. Xo valid argument can 
be brought forward to show why the United States should not be kept 
as free from outbreaks of yellow fever as the city of Havana, its former 
endemic home, has been during the past four years. 

To attain this result the following requirements seem to be essential : 

1. Our physicians, or at least those who are in control, must dis- 
abuse their minds of the impression that black vomit necessarily 
occurs in the majority of cases of yellow fever. 

2. During the epidemic season, viz, from about May 1 to October 
31, and in the epidemic zone, physicians should be required to report 
to the health authorities, immediately, all cases of fever of any kind 
that come under their observation, whether among their patients or 
not, and failure to do so should be made punishable under the law. 

3. The board of health should be authorized to appoint, with 
proper compensation, a commission of three experts, all of whom 
should be men of high reputation as diagnosticians. It should be the 

1 Yellow Fever, La Roche, Philadelphia, 1855, vol. i, p. 590. 



218 YELLOW FEVER. 

duty of this commission to visit without delay all cases of fever 
reported to the health authorities, and the onus of diagnosis should 
rest on the commission and not on the attending physicians. They 
(the commission) should visit each patient daily until the diagnosis 
is established or the patient sent to hospital, and they should for- 
ward promptly to the health department a written report at each 
visit. The commission should determine whether or not the patient 
shall be treated as a possible case of yellow fever, and their decision 
should be final and obligatory on all concerned. 

4. All patients presenting the symptoms of yellow fever, and all 
cases not diagnosed but remaining under suspicion, should be 
promptly removed for treatment to a hospital especially located and 
provided with wire screens and mosquito nets, and the whole or a 
portion of which has been set apart for that purpose. The yellow 
fever wards or hospital should be under the direct control of the 
senior diagnosis commission, and the patients should be treated by 
physicians appointed only on their recommendation and acting under 
their direction. 

5. In exceptional cases, to be determined by the commission, 
patients under observation awaiting diagnosis could be treated in 
their homes beneath mosquito netting, and in rooms properly pro- 
tected with wire screens, until the nature of the case had been finally 
settled to the satisfaction of the commission. 

The commission and not the attending physician should be held 
responsible for the enforcement of all clinical measures necessary for 
the protection of the community, and they should be empowered to 
employ such help as seemed in their judgment to be required. They 
should also be assisted at times by subcommissions appointed on their 
recommendation. 

Under such a system, conscientiously carried out, the occurrence 
of an epidemic of yellow fever in any city would become an impossi- 
bility. Objection can not be made on the ground of expense if the 
members of the diagnosis commission are paid only for every visit 
to a patient; under such an arrangement the cost to the city would 
be trifling when compared with the losses now sustained by indi- 
viduals and the whole community through the failure of practicing 
physicians to recognize and report mild cases of the disease. And 
herein lies the crucial point. The diagnosis must be anticipated 
and the proper precautionary measures be taken before the disease 
has fully declared itself. Diagnoses of malarial remittent, and above 
all of bilious remittent fever, must not be accepted as conclusive 
until the presence of malarial or other parasites has been demonstrated 
to the satisfaction of the members of the diagnosis commission. 
Attention was called two years ago x to the fact that over and over 
again, since the time of Benjamin Rush, yellow fever has stalked 
abroad in our cities, unrecognized, under the guise of bilious remittent 
fever. The time has come when a diagnosis of bilious remittent 
fever should no longer be accepted, for there is no such disease per se. 
We may have malarial fever complicated with jaundice, but this 
should not change the diagnosis of malaria any more than an accom- 
panying icterus would change a diagnosis of typhoid fever. Simi- 
larly a complication of malaria no longer justifies the diagnosis of 

1 Journal Association of Military Surgeons, 1903, No. 4, vol. xiii, pp. 193, 199, and 200. 



YELLOW FEVER. 219 

t3 7 pho-malarial fever, and that term has properly been discarded. 
In numerous instances it is stated in the records of the older epidemics 
of yellow fever that the disease was preceded by, or began as, a bilious 
remittent fever, just as in more recent times physicians have believed 
that typhoid fever began as malarial fever. The conclusion is 
equally untenable in both cases, and the deduction is obvious that 
cases of so-called bilious remittent fever must be regarded and treated 
as cases of yellow fever, unless a satisfactory specific cause for the 
condition can be demonstrated beyond a doubt. It is proper to 
mention here that in every one of the 22 cases of yellow fever pur- 
posely inoculated by the Army Board in Cuba, a diagnosis of bilious 
remittent fever would have been justified if it had not been known 
that they were produced from true cases of yellow fever, for, although 
some of them were severe, black vomit was absent from all. 

It may seem unnecessarily severe to require physicians, under a 

Eenalty, to report all cases of fever coming under their observation, 
ut no other means will attain the desired result, and the enormous 
interests at stake demand that the methods instituted be thorough 
and that they be rigidly carried out. The appointment of a board of 
diagnosis, as has been suggested, will relieve the attending physician 
from the odium that accompanies a diagnosis of yellow fever in a 
doubtful case, and the board, fully appreciating the responsibility 
that rests on them, may be relied on to do their duty. During the dis- 
cussion on yellow fever before the American Public Health Associa- 
tion at its meeting in Washington two years ago, already referred to 
in my remarks, which were badly misquoted, 1 I urged the necessity 
for requiring physicians, under a penalty, to report all cases of fever, 
in order that they might be examined by a board of experts (as was 
done in Cuba) and treated as cases of yellow fever until the diagnosis 
was established. Only last month, in a conversation on this subject 
with a physician from a large city in Texas, he laughingly remarked: 
"We never report our cases of yellow fever until we have about a dozen 
of -them. " 

The present epidemic in and about New Orleans only serves to em- 
phasize the necessity for such regulations as are here suggested, and this 
necessity is further emphasized by the statement in the public press 
of September 5 that " Inspector Brady attributed the continued spread 
of the disease to the unwillingness or inability of physicians to diag- 
nose mild cases of yellow fever, and that physicians of standing and 
ability look for black vomit before making a diagnosis." We have else- 
where 2 cited the occurrence of the same difficulty at Key West in 1889, 
and we again assert that these physicians may be thoroughly con- 
scientious and ablemen, but they are baffled by the differences between 
the aspects of the disease as they actually find it and as they have been 
taught by the best authorities to expect to find it. It is the manifest 
duty of local health authorities, therefore, to relieve the physician of 
the burden of diagnosis and to leave that and the adoption of protec- 
tive measures to the board of expert diagnosticians. 

In this connection I beg to be permitted to call attention to the 
present situation at Jackson Barracks, a station of two batteries of 
Coast Artillery, in New Orleans. By the seventh day of the present 

1 Reports of the Proceedings of American Public Health Association, vol. xxix, 1904, p. 291. 
J Journal Association of Military Surgeons, 1903, vol. xiii, No. 4, p. 201. 



220 YELLOW FEVER. 

month a number of cases of yellow fever had appeared in the neighbor- 
hood and seven of them in a block that approached within 100 feet of 
the officer's quarters. Still the garrison has not been removed and up 
to the present time no single case has occurred among them; even 
should a case or two appear an epidemic is not feared. The reason 
for this is simply that the medical officers know that it is absolutely 
within their power to prevent any epidemic extension of the disease; 
they are constantly on the alert, and all cases of fever are handled in 
the beginning as though they might be yellow fever. 

Again, at Fort Mcintosh, in Laredo, Tex., in 1903, there were only 
5 cases of yellow fever in a command of 1 1 1 officers and men, while 
in the town alongside them over 1,000 cases and more than 100 deaths 
occurred. It was found that the 5 men who became infected had 
violated orders by visiting the town at night without wearing the 
prescribed mosquito head-nets, leather gauntlets, and leggings. 

If, in thp> presence of cases of yellow fever among and around them, 
garrisons of soldiers can be protected from the infection in anything 
like epidemic form, it necessarily follows that the same measures and 
the same degree of vigilance will protect a community, provided the 
physicians do their full duty and they are properly assisted by the 
authorities. The subject is one involving the lives and interests of 
thousands of innocent persons, and the secret of success lies in eternal 
vigilance, with the determination to allow no case, however mild and 
doubtful, to escape the fullest precautions. 




DR. ARISTIDES AGRAMONTE. 



PART IV— REPORTS FROM SANITARY OFFICERS IN HABANA, CUBA, 
DEMONSTRATING THE PRACTICAL VALUE OF THE SCIENTIFIC 
FINDINGS OF MAJ. REED AND HIS ASSOCIATES ON THE YELLOW- 
FEVER COMMISSION. 



Chapter I. 

SANITATION AND YELLOW FEVER IN HABANA. 

Headquarters, Department of Cuba, 

Office of Chief Surgeon, 

Havana, February 8, 1901. 

The Adjutant General of the Department. 

Sir: 



ESPECIALLY FROM THE VIEWPOINT OF THE SANI- 
TARIAN. 

Yellow fever has played such a conspicuous and important part in 
the mortality of Habana that it deserves special consideration. This 
infectious disease may claim Habana as one of its oldest and most 
favored haunts. It was here as early as 1720, if, as I believe, we are 
justified in so regarding the outbreak of that date described by the 
historian Pezuela, apparently imported from Vera Cruz. It there- 
after broke out in occasional epidemics like the historic, ones of 1749 
and 1762, the latter being particularly fatal to the Anglo-American 
army which had just captured the city, and causing the conquerors 
to relinquish their prize in 1763. From that day to this yellow fever 
has been endemic in Habana, hardly noticeable in some years, a mere 
smouldering fire when nonimmunes were few, but quickly lighting 
up into a blaze as soon as the fuel of immigration came within its 
reach. The result has been a thoroughly infected city, a source of 
danger not only to its own inhabitants and the rest of Cuba, but as 
well to all countries having commercial relations with it. 

During the decade 1890-99, the recorded number of deaths was 
4,831, giving an annual average of 483, with a wide range from 1,282 
in 1896 to 103 in 1899. In 1900 the number of deaths was 310. 
Thus yellow fever is not nearly as fatal in Habana as typhoid fever in 
the United States, and its importance would seem to have been very 
much exaggerated, did we not realize that its mortality is not fur- 
nished by the whole population, but only a small proportion thereof, 
that is, the nonimmunes probably never averaging more than 1 
in 10. 

Until a few months ago the mode of propagation of yellow fever 
was uncertain; we were fighting an unknown enemy in the dark, an 

221 



222 YELLOW FEVEE. 

enemy so wily and elusive that we never knew to what extent our 
clumsy and expensive methods of warfare were successful. But, 
very recently, much light has been thrown upon the subject as the 
result of one of the most brilliant medical discoveries of the age. The 
announcement long ago made by Dr. Carlos Finlay, of Habana, that 
mosquitoes were the agent of transmission in yellow fever has been 
verified and scientifically demonstrated by Maj. Walter Reed, Sur- 
geon, United States Army, and his colleagues, in the most conclusive 
manner. It is true that the germ itself, in spite of the claims of 
Sanarelli and his partisans, has not yet been isolated, but this is of 
comparatively little moment to the sanitarian, more concerned with 
prevention than cure. For our purpose, the mosquito is the enemy, 
and all our efforts must be directed against it. This war should be 
waged with a twofold object: the destruction of the malaria-bearing 
anopheles and that of the yellow-fever bearing culex; thus, at the 
same time, eradicating the two diseases which have contributed so 
much to make Habana a byword of reproach among civilized nations. 
Practically, then, the problem consists: First, in finding the haunts 
and breeding places of mosquitoes and the best means of extinguishing 
them ; second, in carefully protecting yellow-fever patients and all non- 
immunes with mosquito bars, so that mosquitoes may not be infected 
by the former and carry the infection to the latter; third, in isolating 
patients, and also, as much as is possible, nonimmunes, so that mos- 
quitoes biting the former may not be able to reach the latter. The 
knowledge that mosquitoes do not travel far, seldom more than a few 
hundred feet if shelter exists, and that each house practically breeds 
its own, simplifies the question. The data being thus plainly stated, 
there does not appear to be insurmountable obstacles in the way, and 
we may confidently expect to see yellow fever stamped out in Habana 
in the course of three or four years after the construction of a good 
sewerage system, provided the same unremitting efforts are con- 
tinued under intelligent medical supervision and with the unrestricted 
help of the State. 

The isolation and protection of patients is a most important 
measure, but hard of successful accomplishment on account of the 
difficulty of discovering and recognizing all cases. Many patients 
among the poorer classes are not seen by physicians, and the expe- 
rience of the last two or three years has led us to believe that many 
cases, especially among young children, are so mild that they pass 
unrecognized or are wrongly diagnosed. From these mild, ambu- 
latory, and consequently unprotected cases the fever is mostly spread. 
It is only when the profession becomes convinced that such cases 
really exist, and that, as foci of infection, they are as dangerous as 
severe cases, that perfect results will be obtained. 

Our present knowledge concerning the agency of the mosquito in 
yellow fever explains much that was obscure before and furnishes 
useful indications to the sanitary physician. For instance, the part 
played by dirt and filth in the breeding and propagation of the fever 
was always problematical; now we know that they have nothing to 
do with it, except inasmuch as they may attract and feed mosquitoes. 
It is certain that in Habana, in 1900, no visible correlation could be 
seen between dirt and yellow fever; the district which first became 
strongly infected lies east and south of the Parque Central, and is 
one of the cleanest and best constructed, while the most insanitary 



YELLOW FEVER. 223 

wards became infected late in the season and only to a slight extent; 
the malodorous district reserved to houses of ill fame did hardly have 
a case. Yellow fever has not followed the poor and unclean, or the 
march of previous infections, but rather the movement of nonim- 
munes; wherever these located, there the infection searched and found 
them, regardless of the hygienic conditions of their premises, the most 
aristocratic apartments on the second and third floors being as liable 
to its invasion as any of the hovels crowded around a patio. 

We also know that digging the ground, either for purposes of cul- 
tivation or construction or, for instance, the laying of sewers, is a 
perfectly harmless operation so far as yellow fever and malaria are 
concerned, provided no water is allowed to stagnate in any of the 
cuts and ditches. The value of this knowledge on the eve of under- 
taking our great work of sewerage can not be overestimated. 

The positive agency of the mosquito in propagating yellow fever 
would naturally argue the noncontagipusness of the disease and the 
inertness of fo mites; but in order that the demonstration might be 
complete, Maj. Reed and colleagues also conclusively proved by 
direct experiment that infected linen, bedding, and effects of all 
kinds are powerless to convey the disease. This discovery must bring 
about a revolution in our methods of disinfection and quarantine in 
yellow fever. Disinfection becomes completely useless, since there 
are no infectious germs to destroy. In a house where a case of yellow 
fever has been under treatment the problem is how to reach the 
mosquitoes which have become infected by biting the patient and 
are still lurking in the vicinity. It is probable that a certain propor- 
tion of mosquitoes, after feeding, fly out in search of water wherein 
to lay their eggs, in the immediate neighborhood, but enough remain 
in the patient's and contiguous rooms to require action. The best 
way to destroy them, so far as now known, is by fumigation. Sul- 
phur fumes are most efficacious, but otherwise so objectionable that 
preference should be given to formaldehyde, which, as we know, is 
much safer and more convenient. It kills mosquitoes in from 10 to 
15 minutes, so that rooms treated with it need not be closed more 
than three or four hours. The good effects of such fumigation seem 
to have been proved in preventing the recurrence of a second case in 
694 out of 885 infected houses in Habana, and by the absence of a 
single case in Santiago de Cuba in 1900, after the epidemic of 1899. 

The duties of quarantine officers have also become singularly sim- 
plified. Since we may assume in practice that the infectious germs do 
not exist outside of man and the mosquito, the disinfection of trunks 
and baggage on account of yellow fever is no longer justifiable; all 
that is required will be the examination of nonimmunes within the 
five days immediately following their last exposure to infection, the 
danger of transmission being from their own persons and in no wise 
from their clothing or baggage. Ships, like houses, are liable to har- 
bor infected mosquitoes and will continue to require fumigation. 

From what precedes it must be evident that the two chief factors 
in the propagation of yellow fever are mosquitoes and nonimmunes. 
Nonimmunes are almost entirely furnished by immigration. Were it 
possible to completely stop it, especially from Spain and the Canary 
Islands, for two or three years, it is almost certain that during that 
short period all germ-bearing mosquitoes could be destroyed, and 
the city thereafter kept as free from infection as Kingston in Jamaica 



224 YELLOW FEVER. 

and San Juan in Porto Rico. Immigration, however, is too valuable 
to the interests of the island to be stopped, or even checked, for the 
sake of stamping out yellow fever, a disease without terror and of 
little consequence to Cubans. It is only possible, then, to take such 
measures as will protect as many nonimmunes as possible without 
interfering in any way with business interests. The plan lately 
adopted is practical and efficient: All nonimmune immigrants who 
do not come in answer to a call from Havana are taken to a detention 
station on the healthiest site around the bay, where they await in 
comfort and safety offers of employment. All employers of labor, or 
as many as it is possible to reach, have been notified of the existence 
of this station and invited to engage there all the hands they need. 
Earnest efforts are made to send as many as possible of these immi- 
grants to the rural districts where most wanted. In this way all are 
benefited: the immigrant who procures work without hardship or 
danger, the city of Havana, which is rid of dangerous nonimmune 
agglomerations, and employers who are enabled to get as many hands 
as they may require with the least trouble and expense. 

The relation which Spanish immigration has borne to yellow fever 
is important and interesting. It has been most active in periods of 
peace and prosperity, becoming small or stopping altogether in years 
of political disturbance and insurrection, and statistics show that the 
spread of yellow fever among civilians is directly proportional to the 
number of immigrants. 

Soldiers, on the contrary, were few in years of peace and contrib- 
uted little to the yellow fever mortality, but in troublous times they 
were greatly and rapidly increased, beginning to arrive as the civil 
immigration began to stop, so that their mortality curve rose as that 
of the civil population fell. Thus, when the last insurrection broke 
out, in 1895, immigration stopped; on the contrary, troops poured 
into Havana, and the result was a very high military mortality in 
1896, 1897, and 1898. When the American troops took possession of 
Havana on January 1, 1899, the whole population was practically 
immune, and, the Spanish troops having departed, cases of yellow 
fever ceased. The American troops formed the only susceptible or 
nonimmune element and disciplinary measures were successful, with 
one slight exception, in preventing their contagion. It therefore 
happened, naturally enough, that only few scattered cases were 
observed during the spring and summer of 1899. As soon as peace 
was assured the current of immigration was resumed, and in greater 
volume than ever. The result was immediately seen in the number of 
cases, which steadily increased from August to December, the number 
for December being larger than for the same month in any previous 
year; this is more striking because the death rate of yellow fever 
generally rises to its maximum in August and September and shows 
a marked decline from October to December. 

During the years 1899 and 1900, 40,384 immigrants arrived at 
Habana, namely 16,260 in 1899 and 24,124 in 1900, a great majority 
of them nonimmunes and at least 50 per cent remaining in the city 
of Habana. They still continue to come at about the same rate. 
With these figures of the largest immigration on record in the same 
space of time, what happened was to be expected and unavoidable, 
namely, an usually large number of cases of yellow fever in the 
summer and fall of 1900 and corresponding high mortality, although 



YELLOW FEVER. 225 

the deaths (310) did not reach the annual average of the past decade. 
The effect of cold weather on the infection was, as usual, well marked ; 
from 74 in October the number of deaths decreased to 57 in Novem- 
ber, 20 in December, and only 7 in January, 1901. 

The subject of immunity against yellow fever is very interesting 
and deserves a few remarks. Immunity is not enjoyed by all 
Cubans, as popularly believed, but only by those residing in cities, 
not by those who have lived from infancy in the interior rural dis- 
tricts. In other words, immunity is only enjoyed by the residents 
of centers where yellow fever is endemic; it is not enough to have 
lived in a tropical climate; one must have lived in an infected locality. 
The inference therefore is strong that immunity is acquired only by 
an attack of the disease; there is no other infectious disease against 
which immunity is obtained in any other way, and there is no reason 
to believe that yellow fever is an exception to the rule. Under the 
former belief that it was acquired by the absorption of germs through 
the respiratory passages, it was possible to conceive the possibility 
of a very slow but constant infinitesimal absorption which might in 
time produce immunity without any apparent fever, but such a con- 
ception is no longer tenable if the germs are introduced directly into 
the blood by the mosquito. Those physicians who assume a priori 
that Cubans, whether they live in the city or country, can not have 
yellow fever, decline to recognize it when they find it in natives ; they 
call it "fiebre de borras" and consider it a special form of malaria, 
which, strangely enough, only occurs in this island. 

Since the great majority of Cubans are immune and immunity is 
only acquired by an attack of the disease, we are compelled to the 
conclusion that nearly all natives of Cuba must have yellow fever 
in their youth — probably in the first few years of their lives. At 
that age the disease appears to be mild and comparatively harmless, 
and we may fairly assume that the 5,000 children annually born in 
Habana have it in such form that it is generally unrecognized by 
physicians who diagnose it under the comprehensive headings of 
malaria, calentura or meningitis. In this connection it is interesting 
to observe that in epidemic years the proportion of deaths among 
children, not diagnosed yellow fever, is noticeably greater. 

Here an interesting question suggests itself. If Cubans have yellow 
fever in infancy in such a mild form as not to endanger life and remain 
immune thereafter, why should they endeavor to eradicate the dis- 
ease in the island, so that their descendants will lose immunity and 
become liable to any epidemic that may break out hereafter? The 
answer is that foreign visitors and immigrants have natural rights 
that Cubans are bound to respect; that epidemics can be guarded 
against and avoided ; and lastly, that although Cuban infants have 
the disease in an apparently mild form, it will probably be found, 
when the matter is investigated and the obscure diagnoses of many 
of the reported cases of death carefully analyzed, that a larger pro- 
portion of deaths among children than is generally believed is due 
to yellow fever or complications therefrom. 

A few words in closing upon the result of treatment of yellow-fever 
cases at Las Animas hospital, an establishment intended for the 
reception and treatment of all contagious diseases, but chiefly yellow 
fever. During the year 1900 it was under the direction of Maj. 
W. C. Gorgas, chief sanitary officer, who devoted to it much of his 
79965°— S. Doc. 822, 61-3 15 



226 YELLOW FEVER. 

valuable time. The hospital is pleasantly situated in the outskirts 
of the city and as completely equipped with material and personnel 
as any hospital of its kind in the United States, American trained 
nurses being in attendance. An ambulance, carrying physician 
and nurse, is always in readiness to go when summoned, and the 
greatest care is taken to save patients all unnecessary fatigue or 
exertion in transit. 

The patients sent to this hospital may be divided in two classes: 
First, Americans (including few other foreigners), the majority of 
them brought there at their own request early in the disease, but 
including also not a few homeless vagabonds and drunkards ; second, 
Spaniards, mostly of the lowest classes, too poor and thriftless to 
belong to any of the quintas de salud. 

It can easily be seen therefore that Las Animas receives most of 
the worst cases, generally after the disease has lasted several days, 
not infrequently the patients being unconscious and occasionally 
moribund, as shown by the fact that out of 58 deaths, 18 occurred 
within three days after admission. During the year, 272 cases 
of yellow fever were admitted; 167 Americans, 74 Spaniards, and 
31 of other nationalities; 214 recovered and 58 died, giving a 
general death rate of 21.33. Taking the three leading and best 
conducted private hospitals in Habana for comparison, namely, 
the Dependientes, Covadonga, and Benefica, we find that during the 
year their yellow fever death rates were 24.35, 27.51, and 24.35 
respectively, each higher than that of Las Animas, although their 
patients, being members of the centros or clubs to which the hospi- 
tals belong, are generally admitted early in the course of the disease 
and therefore in much more favorable conditions for successful 
treatment. 

At Las Animas the death rate of Spaniards was 36.48 and that of 
Americans 12.57, a most remarkable difference when we bear in 
mind that all patients there receive the same identical treatment 
in the same wards. This difference is partly due to the fact that 
Americans are in better physical condition, with greater power of 
resistance, but chiefly to the circumstance that they are admitted 
early and have the full benefit of the treatment. In this respect 
the status of Americans at Las Animas may be fairly compared to 
that of the Spaniards received at the above-mentioned hospitals, 
and yet their mortality is only one-half that of the latter. Such 
results furnish food for reflection. At Las Animas patients are 
treated almost entirely on the expectant plan ; medicines are avoided 
until there is a clear indication for their use; absolute rest, very 
careful dieting, and the constant attention, day and night, of trained 
nurses have been the main features of treatment. The key to 
success in the treatment of yellow fever, I believe, is good nursing 
at the hands of specially trained women. Such nursing is expensive, 
and in Cuba has been practicable, so far, only in few other hospitals, 
but any method of treatment which saves lives is always found to be 
the cheapest. 

V. Havard, 
Major and Surgeon, United States Army, Chief Surgeon. 



Chapter 2. 

REPORT OF THE HABANA YELLOW FEVER COMMISSION. 

Habana, January 3, 1902. 
Sir: In compliance with your request that I should make a report 
of my department, as chairman of the Yellow Fever Commission, for 
the six months ending December 31,1 have the honor to inclose the 
said report. 

Very respectfully, Charles Finlay, 

Chairman of the Yellow Fever Commission. 
Maj. W. C. Gorgas, 

Surgeon, United States Army, 

Chief Sanitary Officer of Habana. 



HALF-YEARLY REPORT OF THE HABANA YELLOW FEVER COMMISSION, JULY TO 

DECEMBER, 1901. 

During the present term (July 1 to Dec. 31, 1901) the Yellow 
Fever Commission of Habana has examined and investigated 118 
cases, reported as follows: 94 yellow fever suspects (37 of which 
were confirmed as " natural yellow fever" and 10 as "experimental 
yellow fever"); 7 suspected glanders (the diagnosis was confirmed 
in 4) ; 4 leprosy (confirmed in 3) ; 6 suspected smallpox (none of 
which were corrfirmed) ; 1 typhus fever (not confirmed) ; 1 relapsing 
fever (not confirmed); 5 reported as tl infectious fever" (in 2 that 
diagnosis was. maintained, inasmuch as these cases, while presenting 
clinical characters suggestive of an infection, could not be identified 
as malaria, typhoid, influenza, and Malta fever, and were therefore con- 
sidered as belonging to the group of "Tropical unclassed fevers). 

The 37 cases diagnosed as "natural yellow fever" have been dis- 
tributed in Table I, so as to differentiate those whose infection had 
originated in this city from others who were brought to Habana, 
already sick or infected, from other parts of this island, and also 
from those who came from foreign ports. 













Table I. 


—1901. 
















July. August. 


September. 


October. 


November. 


December. 


Totals. 




Cases. 


Died. 


Cases. 


Died. 


Cases. 


Died. 


Cases. Died. 


Cases. 


Died. 


Cases. 


Died. 


Cases. 


Died. 


Habana 

Other towns 

(Cuba) 

Foreign ports. . 


7 

6 



3 

1 



7 

3 

1 


1 





9 





2 







1 

1 





2 





1 




o 





o 


23 

10 
4 


6 

1 
1 




13 4 11 1 


9 2 : 2 i 


2 


1 1 





37 


8 



227 



228 



YELLOW FEVER. 
Table II. — Experimental cases. 



August. 


October. 


November. 


Totals. 


Cases. 


Died. 


Cases. 


Died. 


Cases. 


Died. 


Cases. 


Died. 


7 


3 


2 





1 





10 


3 



The wonderfully small number of yellow-fever cases and deaths in 
Habana during the epidemic season of the present year is an unprec- 
edented event, and since it can not be accounted for by any climatic 
variations nor by a lack of nonimmunes or of opportunities for a 
reproduction of the yellow-fever germ through the introduction of 
cases from outside, we are bound to admit that it must be attributed 
to the killing of contaminated mosquitoes wherever they were sup- 
posed to exist, and to the protection of nonimmunes in the vicinity 
of infected houses against the bites of those insects, as the sanitary 
department has been doing since Februar}^. 

MANNER IN WHICH THE INVESTIGATION HAS BEEN CONDUCTED. 

The conclusive demonstration of the mosquito theory — by Dr. Reed, 
a year ago, and by Dr. Guiteras this summer — has made it all the 
more necessary that the investigation of yellow-fever cases should be 
carried out with great care, so as to secure a reliable diagnosis, and to 
discover, if possible, the source whence the infection has been derived. 

The method practiced hj the commission has been as follows: The 
data contained in the original report are carefully gone over at the 
bedside of the patient and additional particulars inquired into in order 
to discover, if possible, the probable source of his infection. A clinical 
history of the case having been obtained from the physician in charge, 
it is minutely scrutinized, and the patient is then carefully examined 
by each of the members present. Particular attention is given to the 
examination of the urine for albumen, and it is believed that, while 
sources of error are avoided, so small a quantity as 10 centigrams of 
pure albumen per liter would not escape detection, as a recognizable 
trace, by the methods employed. The different organs are explored 
to detect or exclude any lesion to which some of the symptoms might 
be attributed, and every circumstance in antecedents of the patient 
is duly taken into account. 

As a rule, the secretary of the commission, before the meeting of the 
board, has collected blood, sputa, pus, or other available material, 
according to the nature of the disease reported, and the said material 
has been examined for malarial parasite or bacteria, tried with the 
Widal test, etc. In the case of private patients, supplementary infor- 
mation has been obtained by the secretary from the attending 
physician, and, if necessary, the latter is requested to be present at the 
meeting of the board. Whenever any doubt remains in the minds 
of the members the decision is deferred and the patient reexamined 
as often as may be necessary. In fatal cases, provided the family or 
friends of the patient do not object, an autopsy is made, notes of the 
findings recorded, and hystological specimens preserved or cultures 
prepared for subsequent examination. The physician in charge is 
always expected to notify the commission or to report the case again 



YELLOW FEVER. 229 

if the subsequent course of the attack should throw some doubt upon 
the decision of the board, in which event a reversal of the first diag- 
nosis would be voted if the majority of the members decided that 
there was occasion to do so. 

USEFULNESS OF EXPERIMENTAL CASES FOR DIAGNOSIS. 

In the diagnosis of mild cases of yellow fever it has been of great 
advantage to the commission to have the support of Dr. Reed's 
observation in one of his experimental cases, showing that an un- 
doubted attack of the disease may run its full course without present- 
ing any trace of albumen in the urine. Similar cases had been 
observed in private practice by members of the commission, and some 
of them have come before the board. The same may be said with 
reference to the importance of the typical fever curve as an element 
of diagnosis in nonalbuminuric cases. 

SOME KNOWLEDGE OF THE LIFE CYCLE AND HABITS OF THE STEGOMYIA 
NECESSARY IN ORDER TO FOLLOW TRACK OF AN EPIDEMIC. 

The importance of ascertaining the source of the infection in every 
confirmed case of yellow fever is self-evident, since the sanitary 
department is thereby enabled to take prompt measures calculated 
to control the propagation of the disease. But that investigation, 
according to the now accepted etiology, can not be successfully 
accomplished without a knowledge of certain details concerning the 
life of the yellow-fever mosquito which are not easily found in the 
current literature on that subject, and it may not be considered out 
of place to recapitulate them in this report. 

The species of gnat which transmits yellow fever (Stegomyia 
tseniata, Theob.-Culex mosquito, R. D.) is diurnal and crepuscular, 
for it may be met with at any hour between daybreak and nightfall, 
and takes its rest during the night. The males never bite nor suck 
blood; the females only do so after they have mated, and never lay 
their ova before having sucked blood. After a complete feed of 
blood the insect will not bite again until all the contents of its stomach 
have been digested or discharged; this process requires from 48 to 60 
hours in summer, but may be delayed 2 or 3 days more in cool 
weather. The wings of the Stegomyia are so small that after a full 
meal it must be unable to fly to any height or even to any consider- 
able distance on a level. It shuns the sunshine, avoids flying across 
open waters, and keeps away from the wind. Its eggs are laid in a 
peculiar manner, some entirely out of the water, so that they are apt 
to remain unhatched during several weeks or months, and yet may 
develop a brood after that lapse of time when they happen to be cov- 
ered with water of a suitable temperature. It is probably by this 
means that the species is propagated during the cooler months of the 
Cuban climate. The Stegomyia breeds in any collection of water 
(a very small quantity is needed) in the yards, gardens, basements of 
nouses, often in the lye water used by washerwomen in this country; 
but also inside of rooms when water has been allowed to stand sev- 
eral days in basins, jugs, or open bottles. A new brood may develop 
in 9 or 10 days if the larvae are abundantly provided with.food (bread 
crumbs seem to agree very well with them), otherwise several weeks 
may elapse before the winged insect emerges from its pupa case. 



230 YELLOW FEVER. 

When the temperature falls to 20° C. the insect is disinclined to 
fly, and below 15° or 10° C. it is benumbed and unable either to fly 
or to bite. It is killed by temperatures below freezing point or 
above 45° C; probably 30° to 32° C. is its optimum temperature. 

The Stegomyia is very domestic in its habits and will not be likely 
to leave the premises on which it has taken up its quarters so long as 
it finds in it the necessary conditions for the completion of its life 
cycle (opportunities for satisfying its craving for human blood, water 
in which it may lay its ova, and an agreeable atmosphere suited to its 
tastes and of the required temperature) In the absence of any of 
those requisites it will migrate into the nearest place where they may 
be satisfied. 

The Stegomyia becomes contaminated and acquires the faculty of 
transmitting the disease only after having bitten a yellow-fever 
patient within the first 5 or 6 days of his attack. During the first 2 
or 3 days of its contamination its bite may sometimes occasion an 
attenuated form of the disease, but after that period the insect loses 
for a while the faculty of inoculating the disease in any form, and it 
is only when 12 or more days have passed since its contamination 
that it acquires the power of producing a well-marked attack of yel- 
low fever, the virulence of its bite being then considerably greater in 
summer than in winter. The contaminated Stegomyia retains there- 
after, during its lifetime (which may last 70 days), the faculty of 
reproducing the disease every time that it chances to bite a non- 
immune. 

The manner in which a nonimmune may become infected is appar- 
ently under the following circumstances: 

(1) By visiting a place where contaminated mosquitoes exist, at a 
time when those insects happen to be in a condition to bite and pre- 
pared to inoculate the disease. 

(2) By the fact that a case of yellow fever has occurred in the 
neighborhood and mosquitoes contaminated from that patient have, 
for some reason, been induced to migrate into the nonimmune's 
dwelling. 

(3) By the conveyance of contaminated mosquitoes in parcels, 
boxes, etc., or, possibly caught under a hat while biting the head of 
a visitor on his way to the nonimmune's house. 

(4) During the hot summer days the Stegomyia is apt to fly out 
into the street, under porches, etc., suggesting the possibility of their 
biting a yellow fever patient on his way to the hospital if the carriage 
or the unprotected ambulance happens to be detained. In such a 
case, the insect, thus contaminated, would afterwards take refuge 
in one of the houses on the road to the hospital, and the nonimmunes 
in that house might, in due time, be inoculated by the infected 
mosquito. 

A PRACTICAL ILLUSTRATION OF THE MOSQUITO THEORY. 

As an illustration of the ways in which the yellow fever may be 
acquired, according to the preceding statements, and of the difficul- 
ties with which the sanitary department has had to contend this 
year in preventing the disease from spreading over the whole city, 
the following instance may be given as one in which the yellow fever 
commission was deeply interested. 



YELLOW FEVER. 231 

In one of our best hospitals in this city (Quinta de Dependientes) 
the upper story of a new building is reserved for yellow fever patients 
and suspects. That floor being divided into a right wing for con- 
firmed cases and the left wing for cases under observation, the landing 
of the stairs occupies the space between the two large screened doors, 
facing each other and opening into each of the two departments. 
Though well provided with wire netting, two defects were subse- 
quently noticed in the disposition of these wards: the height of the 
ceilings, which prevents mosquitoes from being seen when they 
occupy the upper part of the rooms, and the absence of any syphon 
or trap in the pipe leading off the water from a basin under the 
hydrant. Under these conditions, mosquito larvae might be bred 
outside the building where the defective pipe opens and the winged 
insect might find its way into the yellow fever ward, remaining there 
unseen after having bitten some of the patients. In fact, larvse 
were observed by us, on one occasion, in the water jug used in that 
ward. 

On the 14th of August of this year, two nonimmunes were admitted 
into the observation ward with a fever which appeared suspicious 
but only turned out to have been a mild attack of influenza. Both 
were discharged on the 18th. One of them lived at Florida Street, 
No. 24, the other in a bakery in Aguila Street, No. 185, opposite 
the Tacon market. The man from Florida Street was attacked, on 
the 20th (two days after leaving the hospital) with fever and devel- 
oped a mild yellow fever. His house was duly fumigated and all 
the contaminated mosquitoes must have been killed, for no other 
case occurred in that neighborhood. The other man (No. 1), who 
lived at the bakery, was also attacked with yellow fever, but not 
until the 24th (six days after leaving the hospital), and two other 
men (Nos. 2 and 3), who worked in the same bakery and slept in 
rooms near his own, were also attacked, on the same day and the 
next respectively (Aug. 24 and 25). We must therefore infer that 
No. 1 had brought with him from the hospital some of the contami- 
nated mosquitoes which had inoculated him, and the incubation was 
shorter in the two other men than in his own case. The bakery was, 
of course, fumigated and most of the contaminated mosquitoes 
probably killed; but the disposition of the house and of its neighbor- 
hood was particularly unfavorable, and some of the numerous insects 
which had had a, chance of biting one or other of the three simul- 
taneous cases must have escaped and flown across the narrow street 
into the porch of Tacon market, where fruit and flower venders lay 
out their goods on the floor under the porch and sit or stand the 
greater part of the morning waiting for purchasers. Two of those 
flower venders (Nos. 4 and 5) were attacked with yellow fever on the 
7th and 11th of September, respectively; the last of these developing 
into a fatal case, the first of the series. These two men lived in the 
Cerro, where they had their garden near Tulipan Park. 

Their dwelling was fumigated effectively, for no other case of yellow 
fever occurred in the neighborhood. The owner of the bakery on 
Aguila Street lived in a house at the back of it, on Amistad Street, 
No. 136, and (No. 1), when questioned by the members of the com- 
mission at the hospital, had told them that after his attack of influ- 
enza he had first gone to the owner's house. That house was there- 
fore probably infected and duly fumigated ; but from here also some 



232 YELLOW FEVER. 

of the contaminated insects must have escaped and taken refuge in 
a cafe* close by, Amistad Street, No. 130, where the bartender (No. 6) 
was attacked with yellow fever on the 12th of September. This 
house was also fumigated, but the same contaminated insects which 
had bitten this case or others from the same source must have crossed 
Dragones Street and entered another house in the next block, Amistad 
No. 95, where a man servant (No. 7) was attacked with fatal yellow 
fever on the 14th of September. The next two cases occurred in two 
newly arrived immigrants (No. 8 and No. 9) who lived together in a 
room at Ricla, No. 32, a food distance from the infected quarter; but 
they informed us that they were in the habit of going almost every 
evening to a house in the block next to that of (No. 7) Amistad, No 
96, but on the other side of the street, to chat with an immune friend 
of theirs. These two men were attacked on the 21st and 22d of 
September. The killing of mosquitoes at their dwelling proved 
efficacious, for no other cases occurred near Ricla 32; but a few of 
the contaminated insects still remained in the block of (No. 7), for in 
a large tobacco factory occupying the south front of that block two 
of the workmen (No. 10 and No. 11) were attacked on the 28th of 
September. This time, however, the fumigation and killing of the 
mosquitoes within and around the tobacco factory must have killed 
the last of the infected insects, for no other case of yellow fever has 
been reported since in Habana. 

DESIDERATUM. 

The danger of new invasions which might insidiously acquire such 
proportions that they should prove difficult of control, comes prin- 
cipally from the want of a sure landmark by which to recognize even 
the mildest forms of the disease, a want which, it is feared, must 
subsist so long as the germ of the disease has not been definitely 
identified. With the certainty that the said germ is contained in 
the blood of the patient and also in the head of the contaminated 
stegomyia, it was thought that Drs. Reed and Carroll could not 
fail to discover that germ, knowing that they had apparently the 
best of materials to work upon and the assistance of experts well 
trained in the investigation of animal and vegetable germs. Their 
failure to do so has therefore caused general disappointment. The 
Yellow Fever Commission, howerer, considers it one of its duties not 
to let the matter drop, and to avail itself of Dr. Guiteras's permission 
and valuable cooperation for pursuing the search for the yellow-fever 
germ at the laboratory of his experimental station whenever a favor- 
able opportunity for doing so presents itself. 

Charles Finlay, 
Chairman of the Yellow Fever Commission. 

Habana, January 3, 1902. 



Many years before the Yellow Fever Commission was organized, 
Dr. Carlos J. Finlay, of Habana, had formed the opinion that yellow 
fever was conveyed by the bites of mosquitoes and had fixed upon 
the Stegomyia calopus as the culpable agent. On June 30, 1881, 
he began a series of experiments to prove the transmission of the 



YELLOW FEVER. 233 

disease by this insect, believing that he could in this way produce a 
mild type of fever which would convey immunity. He bred the 
mosqvitoes in captivity and developed a technique for transporting 
them and placing them upon the patients, and between the date 
above mentioned and the arrival of the Yellow Fever Commission in 
Cuba he had made 103 experiments of which he regarded a consid- 
erable number as successful. 

In the light of our present exact knowledge of the length of incu- 
bation of yellow fever in man and the considerable period of incuba- 
tion in the mosquito between the time of biting and when she be- 
comes able to transmit the infection, and also the very brief period 
(three days) at the begining of the disease during which alone the 
patient is able to infect the mosquito, it must be recognized that 
probably none of Dr. Finlay's experiments were successful, but none 
the less must credit be given for what Col. Gorgas has termed the 
'''scientific clairvoyance" with which he had conceived his theory 
and the enthusiasm with which he maintained it. 

When Maj. Reed went into Habana to consult him, before begin- 
ning the work of the board, he gave him eggs of Stegomyia calopus 
which he specifically stated were those of the mosquito which con- 
veyed the disease, and the first experiments of the board were made 
with mosquitoes grown from these eggs. As Dr. Finlay was the 
originator of this theory, and was of ^reat assistance to the com- 
mission, the above report of his, which is of scientific as well as his- 
torical value, is published in this place, although it is recognized that 
some of the views expressed by him are at variance with the findings 
of the commission. 



Chapter 3. 

REPORT OF MAJ. W. C. GORGAS, MEDICAL CORPS, UNITED 

STATES ARMY. 

Headquarters Department of Cuba, 
Office of Chief Sanitary Officer of Habana, 

July 12, 1902. 

General: I herewith forward the report of the sanitary depart- 
ment, bringing the account of the work up to May 20 of the present 
year. 

This being the final report of the sanitary department of the city 
of Habana under the military government, it might be useful to 
review, in a general way, the work of the department since its incep- 
tion in 1899. 

The great object of sanitation for Cuba, and particularly for 
Habana, as far as the United States was concerned, was the erad- 
ication of yellow fever. For over 200 years this disease had, at 
short intervals, devastated the Atlantic and Gulf coasts of the 
United States, causing great loss of life, and still greater financial 
loss, due to the entire cessation of commerce which occurred during 
the epidemic. It is estimated that the money loss caused directly 
by the epidemic of 1878, which affected particularly the lower 
Mississippi Valley, amounted to $100,000,000, and in years when 
there was no epidemic quarantines had to be kept up against the 
infected regions around the Gulf of Mexico, which stopped almost 
all travel and greatly interfered with commerce. The United 
States had come to look upon Habana as the particular point from 
which infection was spread. Yellow fever has been continuously 
present in this city since 1762. Every month in every year during 
that time there have been some cases. In all other localities of 
North America where yellow fever occurred, it occurred epidemically; 
that is, the locality was free from the disease for a longer or shorter 
time. In places above the frost line winter always puts an end to 
the disease, and in localities in the Tropics it always terminates after 
a greater or lesser period of years from the exhaustion of the nonim- 
mune material. It was therefore hoped by the military authorities 
that if yellow fever could be controlled in Habana the United States 
would be free from danger of epidemic invasion. 

One of the most prominent objects, then, that the military govern- 
ment had before it during its stay in Cuba was the control of yellow 
fever, and for this nurpose we paid great attention to the improve- 
ment of the hygienic conditions all over the island. But Habana 
being the only endemic focus in the island, and, for that matter, 
anywhere else in North America, the energies of the military govern- 
ment were concentrated at this point. 

None who knew anything of yellow fever had any clear idea how 
its eradication was to be accomplished, but there was a general 
belief and hope that by improving the sanitary conditions the disease 

234 



YELLOW FEVER. 235 

here could be greatly decreased, and possibly in the course of a 
number of j T ears gradually gotten rid of, as has been the case in the 
cities of the United States. But no one, I think, who knew anything 
of yellow fever practically would have ventured to predict that 
much could have been done in this line in the course of three years. 

In Habana the government went vigorously to work, rapidly 
organizing street cleaning, disposal of garbage, and the cleaning of 
premises. In a very few months the streets were as clean as those 
of any modern city and the garbage regularly disposed of. But the 
internal sanitation of houses and the organization of the sanitary 
department for the reporting and control of contagious and infectious 
diseases, and similar matters, took a longer time. 

In the early part of 1899, the first year of the military occupation, 
very little yellow fever occurred. The preceding five years had 
been years of war, and for the last few months the American blockade 
had practically put an end to immigration into Habana, and the 
nonimmune population was pretty well exhausted, so that there 
were few left capable of having this disease. In January, there was 
one death; in February, none; in March, one; in April, two; in 
May, none; in June, one, and in July, two. That is, in the first 
seven months of 1899 there were only seven deaths from yellow 
fever. The military governor of the city, Gen. Ludlow, felt sure that 
the measures which were being taken had pretty well eradicated it. 

But about the 1st of August, Spanish immigration began to pour 
into Habana, and between August and December some 12,000 
immigrants arrived in the city, about 60 per cent of whom settled in 
Habana. This at once started up yellow fever, and by December of 
1899 we were having a severe winter epidemic. This continued 
right along through 1900, during which year we had a very sharp 
epidemic, having in all some 1,400 cases. 

The general sanitary conditions had improved, as indicated by 
the falling death rate, in a very satisfactory manner; but our work 
was evidently having no effect upon yellow fever. This disease was 
under control everywhere else in the island, but the principal means 
of reducing it, the deportation of the nonimmune population, so 
successful everywhere else, was not practicable in Habana. 

By the beginning of 1901 the sanitary department was pretty 
well satisfied that ordinary sanitary measures were having no imme- 
diate effect upon yellow fever. The city during the year 1900 was 
as clean and in as good sanitary condition as it was possible for labor 
to make it, and affairs could not be gotten into better condition until 
after the completion of a sewer system. 

In the summer of 1900 a commission of Army medical officers 
headed by Maj. Walter Reed, United States Army, had been sent to 
Cuba for the investigation and study of yellow fever. Due to the 
financial assistance given by the military governor to this commis- 
sion, they were enabled to experiment on the human subject. They 
took up the theory advanced by Dr. Carlos Finlay of Habana, in 
the year 1880, that the Stegomyia mosquito was the sole means of 
the transmission of yellow fever. Dr. Finlay had maintained this 
theory for some 20 years, and had done considerable experimental 
work in this direction. 

The commission, through elaborate and careful experimentation, 
proved this to be correct, and in February, 1901, Dr. Reed read a 



236 YELLOW FEVER. 

paper before the International Sanitary Congress, in Habana, giving 
the results of their work. This idea was so new and so entirely 
contrary to all former theories on the subject, and, apparently, to 
all former experience, that the paper was received with scant belief. 
I myself had seen the work, and was convinced that the mosquito 
could convey yellow fever, but I was hardly prepared to believe that it 
was the only way, or even the ordinary way, of conveying the disease. 

But all ordinary sanitary measures for the preceding two years 
had been flat failures. Yellow fever at the beginning of 1901 was 
about as bad as it had ever been in Habana at that time of the year. 
The city was infected in every part, and there was present probably 
the largest nonimmune population that had ever before been in 
Habana. 

I had very little hope of accomplishing much; it seemed to me that 
even if the mosquito did convey yellow fever, he could not be gotten 
rid of, and, apparently, from all past experience, the mosquito was 
not the only way, or even the principal way, of conveying the disease; 
but, as he evidently could convey the disease, it was our duty to 
take precautions in this direction. 

The military governor readily granted the necessary appropriation 
and authorized the employment of as large a force as needful for mos- 
quito work. Work was commenced on this line February 4, 1901, 
and pushed in every direction. The results soon began to be appar- 
ent. In January there were seven deaths from yellow fever; in Feb- 
ruary, the first month of mosquito work, five deaths; in March, one 
death; none in April, May, or June; one in July; two in August; and 
two in September, and for the nine months following September, 

1901, not a single case nor a death has occurred from this disease. 
This result convinced the sanitary department that the mosquito not 
only could convey yellow fever, but that it was the ordinary way, 
and the only way, at least in Habana, for the conditions in Habana 
during 1901 were as favorable for a yellow fever epidemic as they had 
ever been. The city had the largest nonimmune population, proba- 
bly, that it had ever contained. Infection was scattered in every 
part of the city; not only so, but the small towns surrounding the 
city were thoroughly infected, and were constantly sending cases 
into the city. We continued the same sanitary measures that had 
been taken during the preceding year, and which had not had the 
slightest effect upon the march of yellow fever; but, in addition, we 
we took measures looking to the Stegomyia mosquito as the means 
of conveying the disease. Immediately after the adoption of these 
measures, yellow fever began to decrease, and by September had 
been entirely eradicated from the city. 

The demonstration is the more effective in Habana from the fact 
that in all other cities of North America yellow fever lasts for a 
greater or lesser number of years, and then disappears from natural 
causes, to reappear again when conditions are favorable. In Habana 
the conditions have been different. For 150 years yellow fever has 
been constantly present in the city. From September, 1901, to July, 

1902, not a single case nor a death has occurred. In the 150 years 
referred to, not any year, probably, can be picked out in which dur- 
ing the same period there were less than 100 deaths. 

This, it seems to me, is a practical demonstration, given in the only 
endemic focus for yellow fever in North America, and in a year when 



YELLOW FEVEE. 237 

the conditions were most favorable for the development of the disease, 
of the fact that the Stegomyia mosquito is the only method of trans- 
mitting it — a fact proved by the Army commission. 

Under Army administration the death rate in Habana has de- 
creased in a marked degree. In 1898, the number of deaths was 
21,252, giving a rate of 91.03; in 1899, the first year of our occupa- 
tion, we had 8,153 deaths, giving a rate of 33.67; in 1900, we had 
6,102 deaths, giving a rate of 24.40; in 1901, we had 5,720 deaths, 
giving a rate of 22.11 ; for the first four months of 1902 there occurred 
1,896 deaths, which if kept up for the year would give 5,688 deaths, 
a rate of 20.68 for the year. 

Thus it can be seen that under the military government, in a little 
over three years the death rate was reduced from 91.03 to 20.68. 
The latter rate would be a favorable one for the better class of cities 
in Europe or the United States. And this has come about without 
making any permanent sanitary installations, such as sewage. The 
city was kept as clean as it was possible for labor to make it, with 
regard to the streets, disposal of garbage, and the interior of the 
houses. But every house in Habana, somewhere under the house, 
still has a cesspool, the flow from which sinks into the surrounding 
ground, and as this has been going on for 400 years, the ground itself 
is as thoroughly saturated with organic matter as is possible. 

The authorities had hardly hoped for such marked improvement 
until this system of cesspools has been done away with by a good 
system of sewage. But apparently the condition referred to has no 
very great effect upon the general health of the city; the improve- 
ment has come about from a careful street cleaning, disposal of garb- 
age, internal sanitation of houses, and rigid control of infectious and 
contagious diseases. 

Our work down here has been a useful lesson in municipal sani- 
tation. The same thing could be accomplished by any community 
anywhere else, if they were willing to spend money and labor upon 
it. No elaborate machinery of any kind is necessary; merely men 
and brooms. 

The primary object of the war with Spain was the liberation of 
Cuba from Spanish domination, but, at the same time, the United 
States had hoped to accomplish a good deal in improving the sanr- 
tary condition of the island. In this she has succeeded beyond her 
utmost expectations, and the results in Cuba have been a new de- 
parture in military conquest. The only other people who bear 
comparison with us in attempting to improve the sanitary condi- 
tions of a tropical country are the English, and neither in Jamaica nor 
in India have they been very successful in this respect. 

Much to our surprise, we find that not only can a native city like 
Habana be made as healthy as the better class of cities in the United 
States, but that our own troops, with proper care, thrive just as 
well in the Tropics as they do in the Temperate Zone. With the 
troops, the health conditions have steadily improved, until at the 
evacuation of Cuba the health rate was better among them than the 
average of troops in the United States. 

Our first year in Cuba, 1898, with an average of 8,345 men, we 
had a death rate from disease of 67.94 per thousand. The health 
conditions steadily improved during the four years of our occupation, 
and for the last three months of 1902, with an average strength of 



238 YELLOW FEVER. 

5,000 men, we had a death rate from disease of 1.76 per thousand. 
This means that the first year of our life in the Tropics we lost 67 
men out of every thousand, from disease; the last year of our stay, 
we had profited by our experience to such an extent that we lost 
only 7 men per thousand. 

From our experience in Cuba, several useful lessons can be de- 
duced. We find that the native in the Tropics, with the same sani- 
tary precautions that are taken in the Temperate Zones, can be just 
as healthy and have just as small a death rate as the inhabitants of 
the Temperate Zone; that to bring this about, no elaborate machinery 
of any kind is needed; that it can be attained by any community, 
no matter how poor, if they are willing to spend sufficient labor in 
cleaning, and observing well-known rules with regard to disease; 
that the North American Anglo-Saxon can lead just as healthy a 
life and live just as long in the Tropics as in the United States. 

But by far the most important sanitary lesson is with regard to 
yellow fever — that this disease is only conveyed by the stegomyia 
mosquito; that the disease can readily be eradicated, even when it 
has gotten a firm hold, and easily kept from establishing itself by 
taking measures looking to the mosquito as its cause. 

I look forward in the future to a time when yellow fever will have 
entirely disappeared as a disease to which mankind is subject, for I 
believe that when the yellow fever parasite has once become extinct 
it can no more return than the dodo or any other species of animal 
that has disappeared from the earth. 

Very respectfully, W. C. Gorgas, 

Major, Medical Corps, United States Army. 

Brig. Gen. Leonard Wood, 

United States Army, Washington, D. C. 



PART V— A FEW GENERAL DIRECTIONS WITH REGARD TO DESTROY- 
ING MOSQUITOES, PARTICULARLY THE YELLOW-FEVER MOSQUITO. 



By W. C. Gorgas, 

Colonel, Medical Corps, United States Army. 1 



As this article is not intended for the reading of people who have 
given any particular attention to the facts at present known of the 
way in which the mosquito carries disease from one person to another, 
I think it best to briefly call attention to the leading points in our 
present knowledge of this subject. 

Malaria and yellow fever are the two great diseases with which the 
mosquito is concerned. They are by far the most important diseases 
in the tropical countries of the Western Hemisphere, and play a great 
part in the sickness of the southern part of the United States. Up to 
25 years ago it was universally believed that malaria was caused by a 
gas, or miasm, arising from the decomposition of dead vegetable mat- 
ter in hot countries, but about that time a French army surgeon in 
Algeria, Laveran by name, noticed that if he looked sufficiently care- 
fully with, his microscope, in the blood of persons suffering from 
malaria, he could almost always find a very small animal parasite. 
This little, living being got into the blood in some way, Laveran did 
not know how, fed upon the red blood corpuscles, and was apparently 
the cause of the disease which we call malaria. Laveran' s discovery 
was a great advance in our knowledge of the disease, and it was 
gradually accepted by aU the medical world. 

A careful search was made for the parasite by many investigators, 
but it could only be found in the blood of human beings suffering from 
malaria. Where else it was bred and how it got into the blood of 
man no one could find out. About this time it was discovered by an 
English army surgeon, Dr. Manson, that a small worm — the Filaria 
sanguinis Jiominis — was introduced into the body by the bite of a mos- 
quito. (This worm causes the disease among human beings known as 
filariasis, and to it are due the enormous and unsightly swellings of 
the legs and other parts of the body seen by our people in Cuba and 
the Philippines. It is, however, a disease very rarely found in the 
United States, and not of much importance to us. I only mention it 
here in connection with my story of the mosquito.) 

About 15 years after the discovery of Laveran that malaria was 
due to an insect in the blood, and of Manson, that a certain worm 
which caused disease was introduced into the human blood by the bite 
of a mosquito, another great English army surgeon, Ronald Ross, 

1 Washington, Government Printing Office, 1904. 

239 



240 YELLOW FEVER. 

discovered that the malarial parasite was found in a certain species of 
mosquito — the anopheles — after the insect had bitten a human being 
suffering from malaria. With his microscope he followed the life 
history of this parasite, from the stomach of the mosquito, through 
the walls of the stomach into the mosquito's body, and finally into its 
salivary glands. In the saliva of the mosquito, the little organism 
was found in large numbers, and when biting man, for the purpose of 
getting blood, the mosquito injects her fatal saliva, just as does the 
rattlesnake when he bites. This discovery of Dr. Ross was demon- 
strated in the most positive manner. 

An Italian living near Rome, in Italy (malaria is very bad in the 
neighborhood of Rome), while suffering from a malarial attack was 
bitten by an anopheles mosquito. This mosquito was then taken to 
London, England, where they have no malaria, and a healthy young 
man, who had never had malaria,was bitten by her. In a few days the 
young man had a well-marked attack of malaria, with the usual symp- 
toms, and the malarial parasite was seen by the microscope circulating 
in the blood of the patient and feeding upon the red blood corpuscles 
of his blood. And, again, men were taken, put into houses, screened 
so that mosquitoes could not get in, and spent weeks in this unhealthy 
part of Italy without getting sick. Yet this particular part of Italy 
is considered so unhealthy that during the summer season neither 
native nor foreigner, who can avoid it, spends a night there. 

A night spent in the Campania used to be thought a certain way to 
contract malaria, the idea being that the foul air from the marshes 
caused the disease. Yet it is now seen that entirely unacclimated men 
can breathe this air with safety, provided only that they live in screened 
houses and are not bitten by mosquitoes. These and similar facts con- 
vinced the scientific world that the malarial organism gets into the 
blood of the human being through the bite of the anopheles mosquito, 
and in no other way. 

Before the year 1900 it was universally believed that yellow fever 
was carried from person to person and spread generally by a germ 
which up to that time had not been discovered. The germ was sup- 
posed to travel from person to person by contact with those sick of the 
disease, or by means of clothing or other articles which had been near 
the sick, and its development was believed to be greatly favored by all 
conditions which increased filth. There were a good many facts in the 
spread of the disease which were difficult to account for under this sup- 
position, but nevertheless it was the best explanation possible, and, 
as I said, was almost universally accepted, both by physicians and 
people generally. 

During the year 1900 the Army of the United States had entire 
control of Habana, at that time the great center of yellow fever for 
the world. An excellent opportunity for investigating the disease 
therefore existed. The Surgeon General of the Army sent to Habana 
a board of Army medical officers for the purpose of investigating 
yellow fever. This board was made up of the following Army doctors : 
Dr. Reed, the president, and Drs. Carroll, Agramonte, and Lazear. 
After much investigation they determined to study the relation of the 
mosquito to yellow fever. Their attention was called to this matter 
by the part that the mosquito had already been proved to play in 
malaria and filariasis, as mentioned above, and also by certain facts 
known in the history of yellow fever epidemics, Pr, Finlay, a prom- 



YELLOW FEVEK. 241 

inent physician of Habana, reasoning from certain peculiarities of 
yellow fever and from experiments which he made, had maintained 
for many years that a certain kind of mosquito in Habana, the stego- 
myia, was the cause of yellow fever, but he had not been able to 
prove it. 

DIRECTIONS WITH REGARD TO DESTROYING MOSQUITOES. 

The Army board of which Dr. Keed was president recognized that 
in Cuba, where they did their work, it would have to be entirely 
evident that the men experimented upon could not get yellow fever 
accidentally in Habana, or anywhere else, but only, if at all, in the 
course of the experiment. They therefore took a piece of unoccupied 
ground about 6 miles from Habana and built there a camp of material 
which could not have been infected with yellow fever. They then 
got men who had never suffered from yellow fever and placed them in 
these tents. It was known that if a man exposed to yellow fever was 
going to have it the disease would develop in less than six days, and 
if he passed through six days safe and sound he was known to have 
escaped that particular exposure. 

The board therefore argued that if they kept their men in this camp 
for a period of two weeks they would be safe from any exposure 
which might have occurred before their coming to the camp. They 
also had to provide means which would insure their men not leaving 
the camp, contracting the disease outside, and thus bringing infection 
into the camp. This was done by a military guard, who allowed no 
one to go out or come in without Dr. Heed's permission. Things were 
now so arranged that if a mosquito was allowed to bite a man, and 
yellow fever developed, the board could be certain that the yellow 
fever was due to the bite of the mosquito alone. They did a great 
deal of experimenting here before they worked out all the details of 
the way in which the mosquito actually conveys yellow fever. They 
finally found out that if a female mosquito of one particular species, 
the stegomyia, was applied to a yellow-fever patient in the first 3 
days of his sickness, and then kept from 10 to 20 days and allowed 
to bite a human being who had never had yeUow fever, he would 
very generally develop the disease within 6 days after the bite. 

They also found out that this same man, before he had been bitten 
by the yellow-fever mosquito, could sleep in the bed in which a patient 
had died of yellow fever, could be covered with a black vomit from a 
yellow-fever patient, or be exposed to the emanations from yellow 
fever in any other way, and as long as he was kept safe from the bite 
of the mosquito he would not have yellow fever; but this same man, 
after all this exposure, if afterwards bitten by an infected yellow-fever 
mosquito, would very certainly catch the disease. I think it would be 
interesting to give some of the details of the work by which this great 
discovery was demonstrated. 

They had a little frame building built in this camp furnished with 
jars and the necessary simple material for breeding mosquitoes. The 
building was carefully screened and guarded, so that mosquitoes could 
not get in nor out. Eggs of this particular species of mosquito were 
obtained and hatched in one of the jars. A female mosquito was 
taken from the brood thus hatched. The male mosquito will not bite, 
and can readily be distinguished from the female with a magnifying 
79965°— S. Doc. 822, 61-3 16 



242 YELLOW FEVER. 

glass by the fact that the male has very heavy feathery feelers (anten- 
nae) growing from his head. The female mosquito selected was put 
into a small glass tube, stoppered with a little cotton, so that she could 
get air freely but not escape, taken to Habana, placed on the hand of a 
patient in the first three days of an attack of yellow fever, and allowed 
to fill herself with blood. She was then brought back to her former 
home, placed in a large glass jar, and allowed to digest the blood she 
had obtained. The jar, covered with a piece of mosquito netting, had 
in it a small saucer with a little water, and a lump of white sugar was 
also provided. Under these conditions the mosquito was furnished 
with all the necessities of life. 

So confident were the men in charge of the mosquitoes that I have 
known them to put their hands in the jars and let the mosquitoes feed 
upon them, up to the fifth or sixth day after the mosquito had bitten 
a yellow-fever patient. The mosquito, you recollect, can not convey 
the disease till from 12 to 20 days have passed from the time of her 
biting the yellow-fever case from which she becomes infected. 

On the other hand, I once saw a party of 12 or 15 doctors in the 
mosquito room one day, when the mosquito-bar covering of the jar 
accidentally came off and the insects escaped into the room. These 
doctors had come from other countries to investigate the subject, and 
were not then convinced that the mosquito carried yellow fever. 
Still, they did not care to put the matter to a practical test in their 
own persons, and got out of the room so rapidly that the wire-screen 
door was broken down during their exit. It happened that the mos- 
quitoes in this jar had never bitten a yellow-fever patient and were not 
infected. 

After the mosquito had been left in this condition for from 10 to 20 
days, it was known that her saliva was capable of transmitting the 
disease. When she was wanted for the purpose of giving somebody 
yellow fever, a man would take a glass tube, slip his hand under the 
mosquito netting, put the mouth of the tube over the mosquito, and 
then fill the mouth of the tube with a cotton stopper, as above 
described. She would then be taken to the man to whom it was 
desired to give yellow fever and who had bravely volunteered for the 
purpose, the cotton stopper taken out, the tube turned upside down 
with its mouth resting on the skin, and the mosquito allowed to settle. 
She would then introduce her biting apparatus and slowly fill herself 
with blood. But before she fills with blood she injects her saliva into 
the wound, just as does the snake in biting. It is this injection of the 
saliva that causes the swelling and the burning sensation that is felt 
at the point where the mosquito bites and which lasts some time after 
she has finished. The injection of the irritating saliva probably has 
the effect of making it easier for the mosquito to get blood. 

Now, it will be remembered that this man who was bitten had been 
kept in the camp for two weeks before he was bitten, and isolated in 
such a way that he could not possibly have contracted yellow fever. 
There were 30 or 40 men in the same camp under exactly the same 
conditions. Three or four days after he was bitten by the mosquito 
he developed a well-marked case of yellow fever, although everybody 
else in the camp remained well. Dr. Reed and his fellow workers 
therefore very naturally believed that that particular mosquito gave 
the man yellow fever. They repeated this test 12 or 15 different times 
with the same result. Nobody else in the camp had yellow fever, 



YELLOW FEVER. 243 

Always within six days after the bite of the mosquito known to be 
infected the man experimented upon had yellow fever. 

To show how a house could become infected with yellow fever the 
board conducted the following experiment: They built a large room 
and screened it so that mosquitoes could not get in or out. (When- 
ever I use the word "screen" here I mean the ordinary wire netting or 
mosquito bar.) The purpose is of course to leave a perfectly free cir- 
culation of air, but to have the meshes of the wire or mosquito bar 
netting so small that a mosquito can not get through. They then 
divided this room into two parts by a wire netting extending from top 
to bottom, so that a mosquito could not pass from one side to the other, 
but at the same time leaving the circulation of air entirely free, the 
desire being to show that if it were any miasm, or emanation, or germ 
floating in the air which caused yellow fever it could freely pass from 
one side to the other of this netting, and that both rooms, as far as 
these emanations were concerned, were in the same condition. 

Now, to show that the building was uninfected, four men were put 
in it who had never had yellow fever, two sleeping on each side of the 
wire netting. They were left there for two weeks and remained per- 
fectly well. Reed then said, "I am now going to infect the room on 
one side of this wire netting with yellow fever and not infect the other 
side." He took the two men out of one side and liberated a half 
dozen infected female Stegomyia mosquitoes on this side. The two 
men still slept and lived on the uninfected side. He then put a 
volunteer on the side with the mosquitoes and left him there for half 
an hour, took him out, and within six days this man developed yellow 
fever, the two men on the other side of the room remaining well. 

He therefore argued that, as the two men who had been for so long 
a time on one side of the wire netting and remained well were breath- 
ing the same emanations, and the only difference was that there were 
mosquitoes on the infected side to which the man had been exposed 
for half an hour, it was very good proof that the mosquito was the 
factor which gave yellow fever. He then said, "Now that I have 
shown you a house infected with yellow fever, I will demonstrate 
how it can be disinfected and rendered safe." He then caught his 
half dozen mosquitoes, bottled them up and put them back into their 
jars, and announced that the building was entirely safe and unin- 
fected, put the two men back into the side which had been infected, 
and the four continued to sleep and live as safely in these quarters 
as they had before the infection. 

The board had another room built and got all sorts of material 
infected by yellow-fever patients from the hospital, clothing worn by 
patients at the time they died of yellow fever, such as mattresses on 
which they died, soiled in every possible way, pillows and pillowcases 
saturated with black vomit, and blankets over which basins of black 
vomit had been poured; in short, material infected by yellow fever in 
every possible way that could be thought of. All this material was 
placed in the room, which was made close and tight with very little 
ventilation, so as to make the conditions most favorable for what was 
ordinarily considered the best way of insuring the spread of yellow 
fever. Volunteers who had never had yellow fever were placed in 
this room, lived and slept there for two weeks at a time, wore this 
clothing, slept on these mattresses, under these sheets, and yet not a 
single case of yellow fever was developed from this contact. The 



244 YELLOW FEVER. 

men who had undergone this exposure were taken out and kept for 
two weeks so as to insure that they had not contracted yellow fever 
from the exposure, and then bitten by infected mosquitoes. They 
always got yellow fever from the bite of the mosquito, but never in 
any other way. 

At this time the military authorities had had entire control of 
Habana for about two years. An Army doctor had been placed in 
charge of the health department and given the means and power to 
do what he thought most likely to free the city from yellow fever. 
Yellow fever in Habana was a disease like consumption in Galveston 
or New Orleans — always there, and always one of the principal causes 
of death in the city. And this had been the state of affairs as long as 
anything had been known with any accuracy, either about yellow 
fever or about the health conditions of Habana; and these things 
were pretty accurately known for more than a hundred years imme- 
diately preceding the time I refer to. When we organized our health 
department, we believed, as did everybody else, that yellow fever was 
caused by filth, dirt, and general insanitary conditions, so we went 
to work doing our very best to correct these conditions. With these 
efforts Habana very rapidly became a healthy city, as much so as 
many of our large cities m the United States, but yellow fever did not 
seem to be affected. 

The second year of our control yellow fever was very severe in 
Habana, but did not attack the native Cuban because he was generally 
acclimated. Only the foreigner, therefore, was subject to the disease. 
During the year 1900 many of our prominent American civilians and 
military officials died of the disease, and the very cleanest and best 
parts of the city and the people who lived best and took the best care 
of themselves were most affected. When the Army Board published 
their discovery to the world the health department of Habana recog- 
nized that it and all the rest of the world had been on the wrong 
track with regard to yellow fever, and they determined to change 
their methods and attack the mosquito as the cause of the disease. 

They had been convinced by the work of the Army board that a 
human being could only get yellow fever by being bitten by a par- 
ticular kind of mosquito — the stegomyia — which had previously 
bitten a man suffering from yellow fever. They therefore arranged 
that as soon as a man sickened with yellow fever employees from the 
department went to the house and screened it with wire netting so 
that those mosquitoes that were in the house could not get out and 
those outside could not get in. A smudge was then made of sulphur, 
tobacco, or insect powder, as best suited to the circumstances, in the 
affected house, and in all those immediately around it, with the 
intention of killing all mosquitoes present. By this method it was 
hoped that both the mosquitoes that had bitten the man and caused 
the disease would be killed, and also those that had bitten the man 
after he was taken sick, and had thus become themselves infected 
and able to spread the disease. For the purpose of doing this 
screening a building was arranged very much like a fire station in one 
of our cities, where wagons, wire screens, carpenters, and men with 
material for making a smudge, were always kept on duty, who pro- 
ceeded at once to the place where a yellow fever case was reported to 
exist. 



YELLOW FEVER. 245 

This method was very successful in its results. After its adoption 
very few cases occurred where the disease spread from the person 
infected to others in the neighborhood. It was also determined to 
destroy as many as possible of the yellow fever mosquitoes in the 
city. It was known that the female mosquito had to have water 
on which to lay her eggs, and that these eggs could not hatch without 
water; that this water had to be very quiet and well protected for the 
hatching process to take place; that the eggs took about three days 
to hatch; that after hatching the insect had to live the life of a fish 
in this water for five or six days. During this fish stage they are 
known as larvse, and are well known to everybody in the South, for 
they are nothing but the common wigglers always found in standing 
rain water during the summer months. Now, while in this wiggler 
stage the insect has to have air, and for this purpose must every 
little while come to the surface. At the end of five or six days the 
wiggler changes into the full-grown mosquito. 

It is known that this particular species of mosquito — the stegomyia, 
or the yellow fever mosquito — lives and breeds almost altogether in 
houses and in their immediate neighborhood, and does not leave the 
house for any great distance. With this knowledge of its life history, 
the department found it easiest to destroy the mosquito in its wiggler 
stage, and the most useful means in this direction they found to be 
the doing away with all the little deposits of water in and near inhab- 
ited houses, which the wiggler must have in order to develop into the 
mosquito. The methods herein described were not settled upon, as 
might appear from this account, all at once and at the beginning, but 
many other methods of waging war against the mosquito were tried, 
found impracticable, and dropped. 

With the object of doing away with the breeding places of the 
yellow-fever wiggler, all the houses and yards of Habana were carefully 
examined and all tin cans, empty bottles, and trash of the same kind, 
which were generally found filled with rain water and full of yellow 
fever mosquito larva?, were carefully carted off. Then the necessary 
openings in all cisterns were covered with mosquito netting, so that 
the mosquitoes could not get in to lay their eggs. Among the poorer 
people, who had only barrels and other similar receptacles for rain 
water (and in Habana every family had something of this kind), the 
health department arranged these necessary receptacles for them by 
placing a wooden cover on the barrel, leaving a hole in the center of 
this cover for the entrance of water, and covering the hole with wire 
netting, so that mosquitoes could not get in. To enable them to draw 
off the water without opening the barrel a cheap wooden spigot was 
placed in the lower part. 

Xow, from the peculiarity of the wiggler, that he has to come to the 
surface of the water even' few seconds to get air, if we put anything 
on the surface of the water that prevents him getting this air, he 
drowns just as certainly as a man would who is kept under the water. 
Ordinary kerosene oil, a tablespoonful or two to a cistern, spreads 
over the surface of the water and kills the wiggler in this way. He 
can not break through the scum of oil to get air. But oil very rapidly 
evaporates and has frequently to be renewed. So oil was only used 
in Habana where no other method was successful. The privy pits in 
all the houses there were in the center of the court, covered generally 
with heavy flagstone. These pits, not being in general accessible to the 



246 YELLOW FEVER, 

inspectors, had to be treated with oil. Once a month a couple of 
ounces of oil were poured into the pipes leading to the pits. 

To insure that these methods and ordinances were carried out, the 
city was divided into districts of about a thousand houses each, so 
that an inspector would get over each district in the course of a month, 
inspecting at the rate of about 30 houses a day. This inspector 
had with him two men who used the oil as above described. He had 
with him printed blanks on which he entered the condition of the 
premises as to wigglers. These reports were turned in every night 
to the office of the health department and were consolidated from day 
to day. At the end of the month we could therefore tell the condition 
of Habana as to wigglers. At the first report on this subject (I think 
in March, 1901) we found that we had in Habana in the neighbor- 
hood of 26,000 different water deposits which contained wigglers, 
most of them of the yellow-fever variety. 

After once going over the city and carefully explaining to the 
people the dangers of allowing wigglers on their premises, and after 
having fixed up for the poor all the water barrels which they were 
obliged to keep for holding their rain water, the mayor of the city 
issued an ordinance stating that anybody who bred wigglers on his 
premises would be fined $10. These two methods of destroying 
yellow fever mosquitoes, namely, that of killing the grown mosquito 
in the neighborhood of every yellow fever patient with a smudge and 
of looking after the wigglers in all rain water deposits about the house, 
were steadily enforced during the year 1901. The results were better 
than we had dared to hope. Few cases occurred in which yellow 
fever spread from a case cared for in this way. Yellow fever rapidly 
decreased, and on September 28, 1901, the last case of yellow fever 
occurred in Habana, and since that time — now more than two years — 
not a single new case has developed in the city. 

There were still, of course, a great many yellow fever mosquitoes 
in Habana, but these methods of destroying the wigglers had greatly 
decreased the numbers of mosquitoes. The report of January, 1902, 
after about ten months of this mosquito work, showed that within 
the city limits less than 300 premises had wigglers upon them. This 
I think a very fair measure of the results accomplished by one year's 
work, namely, that the number of deposits containing wigglers had 
been decreased from about 26,000 to about 300. 

I think it is evident that the disappearance of yellow fever from 
Habana was due solely to this mosquito work. Remember that it 
was an every-day disease in Habana, and had been so for more than 
a hundred years, just as consumption is in New Orleans, a city of 
about the same size as Habana. Now, if some method should be 
adopted against consumption in New Orleans, and systematically 
put in operation in the city against that disease, and at the end of a 
year it could be shown that no new cases of consumption were occur- 
ring in New Orleans, and at the end of two years and a half it could 
be further shown that under the continuance of the same measures 
the disease had entirely disappeared from the city, and no new cases 
had occurred, I should think that we would all be at once convinced 
that the disappearance of consumption from New Orleans was due to 
the efficacy of the measures adopted. 

In Habana, even now, a case or two of yellow fever comes in every 
month from Mexico and other infected regions which have a con- 



YELLOW FEVEE. 247 

siderable trade with Habana. The ships are carefully inspected by 
the quarantine authorities, just as is done in our country. If a 
person sick of yellow fever, or suspected yellow fever, is discovered, 
he is landed at the city wharf, in the heart of the business district, 
placed in an ambulance, carried to the yellow fever hospital, which 
is well within the city limits, and treated there. The only precau- 
tion taken is to see that Habana mosquitoes do not get an oppor- 
tunity to bite him. The authorities at Habana thoroughly believe 
that if they can prevent mosquitoes from biting a yellow fever patient 
the city will be entirely safe in handling him and taking care of him. 

In 1901, during the height of the yellow fever work at Habana, a 
town of about 5,000 inhabitants, some 12 miles from the city, became 
badly infected with yellow fever. This town, Santiago de las Vegas, 
was practically a suburb of Habana, and the business communication 
with the city was very intimate. We found that people who were 
working at Santiago de las Vegas were constantly getting sick of 
yellow fever, and as soon as they found themselves sick would come 
into Habana to the homes of their friends and relatives to be taken 
care of. In order to do away with this source of danger, a large force 
of men was put at work at Las Vegas, on the lines above described. 
The whole town was systematically gone through from house to house, 
and at the end of about six weeks of this work the disease was entirely 
wiped out and we had no more trouble with infection from Las Vegas. 
1 mention this as showing the possibility of taking a small town and 
getting rid of the disease rapidly by mosquito work. 

We had other mosquito work going on in the suburbs of Habana, 
among the truck gardens and irrigated fields where grass was grown. 
But the yellow-fever mosquito does not breed to any great extent in 
such places, and I do not think this work had much effect upon the 
yellow fever. But malaria, as I have above mentioned, is also carried 
exclusively by a mosquito named the ' ' anopheles." Now, this malarial 
mosquito likes to breed in places where there are little puddles of 
water, cow tracks, horse tracks, and similar depressions in grassy 
ground, and the work in the suburbs had its principal effect upon this 
mosquito. It was not desirable to stop irrigation, as the livelihood of 
all these small farmers depend upon it, but by taking advantage of 
the fact that a deposit of water had to remain undisturbed at least 10 
days to breed a mosquito, we could allow them to irrigate freely, pro- 
vided the water did not remain longer than a week. The health de- 
partment had all this area arranged with shallow, superficial ditches 
which would not interfere with irrigation, but would allow rapid 
drainage when the water was taken off. All pools and puddles which 
had no economic use were kept drained, and ditches and streams kept 
clean of grass and obstructions. 

After once getting the country cleaned up at public expense, and 
the matter explained to the farmer, he was fined in the same way as 
the householder in the built-up portion of the city, if wigglers were 
discovered on his premises. TV hire I do not think that these measures 
aided us particularly in yellow fever, they had a marked effect upon 
malaria. In 1900, the year before the mosquito work commenced, we 
had in Habana 325 deaths from malaria. During 1901, the year in 
which mosquito work was commenced, we had 151 deaths from 
malaria. In 1902, the second year of mosquito work, Dr. Carlos 
Finlay, the health officer of Cuba, reported 77 deaths from malaria in 



248 YELLOW FEVER. 

Habana, and up to the 1st of November in 1903, the third year of 
mosquito work, Dr. Finlay reported 45 deaths from malaria. 

This mosquito work of the Habana health department, I hold, 
demonstrates the practicability of eliminating in the Tropics the two 
diseases malaria and yellow fever, and I believe if the attention of the 
people at large in our own country were generally attracted to the 
danger of transmitting disease by the mosquito, and the practicability 
of destroying them, we could very generally eliminate these two 
diseases from our own country. 

And now to the reason for writing this article. I thought an account 
of the relations of mosquitoes to disease, given in simple terms, readily 
understood by those who are not doctors, might held people generally 
in making an attempt to get rid of mosquitoes, each man about his 
own house. I will now proceed to make suggestions in this direction. 
And in order to make myself entirely clear will repeat a good deal, 
and enlarge upon what I have already said. 

The work of the Army medical board of which Maj. Walter Reed 
was president, showing that a particular species of mosquito was the 
only means of transmitting yellow fever, is now pretty generally 
accepted by all the scientific world. Based upon this knowledge, 
certain methods were adopted by the Army medical officers in Habana, 
Cuba, which resulted in eradicating yellow fever from that city. 
During the fall of 1903 yellow fever was introduced from Mexico and 
became quite widely spread through western Texas. It is thought 
that a few general rules, based upon the knowledge acquired by the 
Army board and the experience of the Army medical officers in Habana, 
may be of use in assisting individuals and towns in freeing themselves 
from infected mosquitoes during the present winter and coming 
spring. Otherwise, it seems highly probable that yellow fever, at 
some point in Texas, will again develop as the warm weather comes on. 
This would come about from the fact that the infected mosquito can 
very readily live through the winter in the latitude of Laredo. 

As yellow fever can only be spread by a particular species of mos- 
quito, it follows that if there are none of these mosquitoes about, 
yellow fever can not spread. The danger in Texas is that the steg- 
,omyia mosquitoes, that have bitten people with yellow fever, will live 
through the winter and spread another epidemic as the warm weather 
comes on by biting people who have not had the disease. This mos- 
quito, from its nature, stays immediately about the house and in the 
rooms, and seldom or never wanders far. It was found in Habana 
that by destroying all the mosquitoes in each house where yellow 
fever occurred the disease was always stopped in that particular 
neighborhood. It is probable, therefore, that if each householder in 
whose house yellow fever has occurred during the past fall will 
destroy all the mosquitoes in his house he will be free from the old 
infection next spring. This can readily be done by closing the room 
and making a smudge in it of sulphur or tobacco. Care should be 
taken to paste all the cracks up with paper, so that the smudge will 
be confined to the room fumigated, and the pan in which the smudge 
is made placed on a little earth, so that it can not set the floor on fire. 

With sulphur, about a pound to a room 10 feet square, should be 
used, and with tobacco, about half a pound. To start the sulphur 
burning a couple of tablespoonfuls of alcohol should be poured on 
before applying the match. Sulphur should be used unless the room 



YELLOW FEVER. 249 

contains valuable material which might be injured by it. The fumes 
of tobacco hurt nothing, but leave a disagreeable odor. The fumes 
of ordinary Persian insect powder hurt no tiling and leave no odor, but 
it does not always kill the mosquitoes and care has to be taken to 
sweep them up afterwards. A couple of hours will be time enough to 
keep the room closed. After that time it can be opened, aired, and 
occupied. In towns, this method should be carefully carried out dur- 
ing the winter by the town authorities. Not only the houses in which 
yellow fever is known to have occurred, but every house in the infected 
town should be treated in this way. We found in Habana that a squad 
of five men, under intelligent direction, could easily fumigate a 10- 
room house in two hours. It should be arranged so that the whole of 
the infected town should be gone over before the 1st of April. 

The above directions cover the points with regard to killing infected 
mosquitoes, and thereby preventing the liability of a new epidemic 
next summer from the old mosquitoes left over from last year. But 
it is even more important to prevent the breeding of a new crop of 
stegomyia mosquitoes, and this can be very readily done without very 
great effort. 

The female stegomyia mosquito always seeks some small body of 
well-protected fresh water in which to lay her eggs. On the surface 
of this water she lays about 60 or 70 eggs. These, in warm weather, 
in three days hatch out into the ordinary wiggler, and the wiggler in 
five or six days develops into the full-grown mosquito. From the 
laying of the egg to the development of the full-grown mosquito takes 
about eight days in hot weather. Water is as necessary to the insect 
as it is to a fish. It is essentially a water insect during this period, 
though it is an air-breathing insect, too, and has to come to the surface 
of the water every few seconds to get air. 

As I stated above, the stegomyia seeks particularly deposits of clean 
water, and is essentially a house mosquito, breeding either in the 
house or very close to it, in such places as cisterns and rain-water bar- 
rels, and in anything likely to catch and retain rain water, such as old 
bottles or cans, or gutters under the roofs of houses, etc. Xow, if 
every householder will give a little attention to see that there are no 
such deposits about his house, he will be free from the stegomyia mos- 
quito, and no one will contract yellow fever in his house, even if cases 
are introduced into it from elsewhere. If necessity obliges him to 
keep a cistern or barrels of rain water, if he will arrange the receptacle 
so that the mosquito can not get in to lay her eggs, it will be entirely 
safe. In the cistern this can be done by covering the top tightly, with 
the exception of a hole for ventilation, and one for the entrance of the 
water, and these two holes should be covered with wire netting. The 
netting should be not larger than 16 meshes to the inch. A larger 
mesh than this will allow the smaller size of stegomyia to pass through. 

Water barrels can be arranged in the same way, a tight-fitting top 
put on, with a wire mesh over the hole for the entrance of the water, 
and a cheap snigot put in the bottom for drawing off water. If he 
finds wigglers in any of the vessels of water which he is obliged to 
keep, he can know that his cover is imperfect, and that the female 
mosquito has gotten in there in some way to lay her eggs. Small 
deposits about the yard and in the immediate neighborhood should be 
swept out or drained away. A deposit of water in Texas would have 
to stand at least 10 days to breed a mosquito. For this reason, if the 



250 YELLOW FEVER. 

householder is not able to arrange his water vessels as above sug- 
gested he could avoid breeding stegomyia mosquitoes by having these 
vessels emptied once a week. But if the method of emptying is used, 
the larvae should be carefully washed out or the vessel left to stand 
empty for more than an hour. If this precaution is not taken, a con- 
siderable number of the larvae will be left adherent to the bottom and 
sides and will live if the vessel is at once refilled. Kerosene oil is 
fatal to the larvae if two or three tablespoonfuls are spread over the 
surface of the water. 

As I said before, the larvae have to come to the surface every few 
seconds to get air, and as they are unable to break through the film 
of oil they die of suffocation, but the oil evaporates ve^ rapidly and 
should be renewed every week. Much the better method is either to 
get rid of the deposit of water or protect it in the above-mentioned 
manner. Oil should only be relied upon in treating deposits in a 
building or its immediate neighborhood which can not be managed in 
one of the above-mentioned methods. Privy pits which contain water 
were the only places in Habana in which we habitually resorted to oil. 

In towns these methods should be enforced by regular and syste- 
matic inspections. In most towns there are ordinances against pigs 
and pigsties. A hog is considerably larger than a mosquito wiggler, 
but with a little care an inspector will soon learn to discover the wig- 
glers almost as easily as the hogs. And the householder should be 
taught that the wiggler causes a great deal more annoyance to himself 
and his neighbors than the hog does, and is infinitely more dangerous 
to health. And the ordinances should hold the householder as strictly 
to account for breeding wigglers on his premises as for having a pigsty 
with a litter of pigs. The larger deposits, a hundred yards or more 
away from the house, such as small ponds and swampy places, while 
breeding mosquitoes that cause a great deal of annoyance, will not 
breed the stegomyia to an extent sufficient to be dangerous to the 
house. They should be managed by the town authorities on the same 
general principles — to drain wherever possible. 

O 



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